My POWER9 CPU Core Layout

So, following on from my post on Sensors on the Blackbird (and thus Power9), I mentioned that when you look at the temperature sensors for each CPU core in my 8-core POWER9 chip, they’re not linear numbers. Let’s look at what that means….

stewart@blackbird9$ sudo ipmitool sensor | grep core
 p0_core0_temp            | na                                                                                                               
 p0_core1_temp            | na                                                                                                               
 p0_core2_temp            | na                                                                                                               
 p0_core3_temp            | 38.000                                                                                                           
 p0_core4_temp            | na          
 p0_core5_temp            | 38.000      
 p0_core6_temp            | na          
 p0_core7_temp            | 38.000      
 p0_core8_temp            | na          
 p0_core9_temp            | na          
 p0_core10_temp           | na          
 p0_core11_temp           | 37.000      
 p0_core12_temp           | na          
 p0_core13_temp           | na          
 p0_core14_temp           | na          
 p0_core15_temp           | 37.000      
 p0_core16_temp           | na          
 p0_core17_temp           | 37.000      
 p0_core18_temp           | na          
 p0_core19_temp           | 39.000      
 p0_core20_temp           | na          
 p0_core21_temp           | 39.000      
 p0_core22_temp           | na          
 p0_core23_temp           | na        

You can see I have eight CPU cores in my Blackbird system. The reason the 8 CPU cores are core 3, 5, 7, 11, 15, 17, 19, and 21 rather than 0-8 or something is that these represent the core numbers on the physical die, and the die is a 24 core die. When you’re making a chip as big and as complex as modern high performance CPUs, not all of the chips coming out of your fab are going to be perfect, so this is how you get different models in the line with only one production line.

Weirdly, the output from the hwmon sensors and why there’s a “core 24” and a “core 28”. That’s just… wrong. What it is, however, is right if you think of 8*4=32. This is a product of Linux thinking that Thread=Core in some ways. So, yeah, this numbering is the first thread of each logical core.

[stewart@blackbird9 ~]$ sensors|grep -i core
 Chip 0 Core 0:            +39.0°C  (lowest = +25.0°C, highest = +71.0°C)
 Chip 0 Core 4:            +39.0°C  (lowest = +26.0°C, highest = +66.0°C)
 Chip 0 Core 8:            +39.0°C  (lowest = +27.0°C, highest = +67.0°C)
 Chip 0 Core 12:           +39.0°C  (lowest = +26.0°C, highest = +67.0°C)
 Chip 0 Core 16:           +39.0°C  (lowest = +25.0°C, highest = +67.0°C)
 Chip 0 Core 20:           +39.0°C  (lowest = +26.0°C, highest = +69.0°C)
 Chip 0 Core 24:           +39.0°C  (lowest = +27.0°C, highest = +67.0°C)
 Chip 0 Core 28:           +39.0°C  (lowest = +27.0°C, highest = +64.0°C)

But let’s ignore that, go from the IPMI sensors (which also match what the OCC shows with “occtoolp9 -LS” (see below).

$ ./occtoolp9 -SL
Sensor Details: (found 86 sensors, details only for Status of 0x00)                                           
     GUID Name             Sample     Min    Max U    Stat   Accum     UpdFreq   ScaleFactr   Loc   Type 
....
   0x00ED TEMPC03………     47      29     47 C    0x00 0x00037CF2 0x00007D00 0x00000100 0x0040 0x0008
   0x00EF TEMPC05………     37      26     39 C    0x00 0x00014E53 0x00007D00 0x00000100 0x0040 0x0008
   0x00F1 TEMPC07………     46      28     46 C    0x00 0x0001A777 0x00007D00 0x00000100 0x0040 0x0008
   0x00F5 TEMPC11………     44      27     45 C    0x00 0x00018402 0x00007D00 0x00000100 0x0040 0x0008
   0x00F9 TEMPC15………     36      25     43 C    0x00 0x000183BC 0x00007D00 0x00000100 0x0040 0x0008
   0x00FB TEMPC17………     38      28     41 C    0x00 0x00015474 0x00007D00 0x00000100 0x0040 0x0008
   0x00FD TEMPC19………     43      27     44 C    0x00 0x00016589 0x00007D00 0x00000100 0x0040 0x0008
   0x00FF TEMPC21………     36      30     40 C    0x00 0x00015CA9 0x00007D00 0x00000100 0x0040 0x0008

So what does that mean for physical layout? Well, like all modern high performance chips, the POWER9 is modular, with a bunch of logic being replicated all over the die. The most notable duplicated parts are the core (replicated 24 times!) and cache structures. Less so are memory controllers and PCI hardware.

P9 chip layout from page 31 of the POWER9 Register Specification

See that each core (e.g. EC00 and EC01) is paired with the cache block (EC00 and EC01 with EP00). That’s two POWER9 cores with one 512KB L2 cache and one 10MB L3 cache.

You can see the cache layout (including L1 Instruction and Data caches) by looking in sysfs:

$ for i in /sys/devices/system/cpu/cpu0/cache/index*/; \
  do echo -n $(cat $i/level) $(cat $i/size) $(cat $i/type); \
  echo; done
 1 32K Data
 1 32K Instruction
 2 512K Unified
 3 10240K Unified

So, what does the layout of my POWER9 chip look like? Well, thanks to the power of graphics software, we can cross some cores out and look at the topology:

My 8-core POWER9 CPU in my Raptor Blackbird

If I run some memory bandwidth benchmarks, I can see that you can see the L3 cache capacity you’d assume from the above diagram: 80MB (10MB/core). Let’s see:

[stewart@blackbird9 lmbench3]$ for i in 5M 10M 20M 30M 40M 50M 60M 70M 80M 500M; \
  do echo -n "$i   "; \
  ./bin/bw_mem -N 100  $i rd; \
done
  5M    5.24 63971.98
 10M   10.49 31940.14
 20M   20.97 17620.16
 30M   31.46 18540.64
 40M   41.94 18831.06
 50M   52.43 17372.03
 60M   62.91 16072.18
 70M   73.40 14873.42
 80M   83.89 14150.82
 500M 524.29 14421.35

If all the cores were packed together, I’d expect that cliff to be a lot sooner.

So how does this compare to other machines I have around? Well, let’s look at my Ryzen 7. Specifically, a “AMD Ryzen 7 1700 Eight-Core Processor”. The cache layout is:

$ for i in /sys/devices/system/cpu/cpu0/cache/index*/; \
  do echo -n $(cat $i/level) $(cat $i/size) $(cat $i/type); \
  echo; \
done
 1 32K Data
 1 64K Instruction
 2 512K Unified
 3 8192K Unified

And then the performance benchmark similar to the one I ran above on the POWER9 (lower numbers down low as 8MB is less than 10MB)

$ for i in 4M 8M 16M 24M 32M 40M 48M 56M 64M 72M 80M 500M; \
  do echo -n "$i   "; ./bin/x86_64-linux-gnu/bw_mem -N 10  $i rd;\
done
  4M    4.19 61111.04
  8M    8.39 28596.55
 16M   16.78 21415.12
 24M   25.17 20153.57
 32M   33.55 20448.20
 40M   41.94 20940.11
 48M   50.33 20281.39
 56M   58.72 21600.24
 64M   67.11 21284.13
 72M   75.50 20596.18
 80M   83.89 20802.40
 500M 524.29 21489.27

And my laptop? It’s a four core part, specifically a “Intel(R) Core(TM) i5-10210U CPU @ 1.60GHz” with a cache layout like:

$ for i in /sys/devices/system/cpu/cpu0/cache/index*/; \
   do echo -n $(cat $i/level) $(cat $i/size) $(cat $i/type); \
     echo; \
   done
   1 32K Data
   1 32K Instruction
   2 256K Unified
   3 6144K Unified 
$ for i in 3M 6M 12M 18M 24M 30M 36M 42M 500M; \
  do echo -n "$i   "; ./bin/x86_64-linux-gnu/bw_mem -N 10  $i rd;\
done
  3M    3.15 48500.24
  6M    6.29 27144.16
 12M   12.58 18731.80
 18M   18.87 17757.74
 24M   25.17 17154.12
 30M   31.46 17135.87
 36M   37.75 16899.75
 42M   44.04 16865.44
 500M 524.29 16817.10

I’m not sure what performance conclusions we can realistically draw from these curves, apart from “keeping workload to L3 cache is cool”, and “different chips have different cache hardware”, and “I should probably go and read and remember more about the microarchitectural characteristics of the cache hardware in Ryzen 7 hardware and 10th gen Intel Core hardware”.

OCC and Sensors on the Raptor Blackbird (and other POWER9 systems)

This post we’re going to look at three different ways to look at various sensors in the Raptor Blackbird system. The Blackbird is a single socket uATX board for the POWER9 processor. One advantage of the system is completely open source firmware, so you can (like I have): build your own firmware. So, this is my Blackbird running my most recent firmware build (the BMC is running the 2.00 release from Raptor).

Sensors over IPMI

One way to get the sensors is over IPMI. This can be done either in-band (as in, from the OS running on the blackbird), or over the network.

stewart@blackbird9$ sudo ipmitool sensor |head
occ                      | na         | discrete   | na    | na        | na        | na        | na        | na        | na        
 occ0                     | 0x0        | discrete   | 0x0200| na        | na        | na        | na        | na        | na        
 occ1                     | 0x0        | discrete   | 0x0100| na        | na        | na        | na        | na        | na        
 p0_core0_temp            | na         |            | na    | na        | na        | na        | na        | na        | na        
 p0_core1_temp            | na         |            | na    | na        | na        | na        | na        | na        | na        
 p0_core2_temp            | na         |            | na    | na        | na        | na        | na        | na        | na        
 p0_core3_temp            | 38.000     | degrees C  | ok    | na        | -40.000   | na        | 78.000    | 90.000    | na        
 p0_core4_temp            | na         |            | na    | na        | na        | na        | na        | na        | na        
 p0_core5_temp            | 38.000     | degrees C  | ok    | na        | -40.000   | na        | 78.000    | 90.000    | na        
 p0_core6_temp            | na         |            | na    | na        | na        | na        | na        | na        | na    

It’s kind of annoying to read there, so standard unix tools to the rescue!

stewart@blackbird9$ sudo ipmitool sensor | cut -d '|' -f 1,2
 occ                      | na                                                                                                               
 occ0                     | 0x0                                                                                                              
 occ1                     | 0x0                                                                                                              
 p0_core0_temp            | na                                                                                                               
 p0_core1_temp            | na                                                                                                               
 p0_core2_temp            | na                                                                                                               
 p0_core3_temp            | 38.000                                                                                                           
 p0_core4_temp            | na          
 p0_core5_temp            | 38.000      
 p0_core6_temp            | na          
 p0_core7_temp            | 38.000      
 p0_core8_temp            | na          
 p0_core9_temp            | na          
 p0_core10_temp           | na          
 p0_core11_temp           | 37.000      
 p0_core12_temp           | na          
 p0_core13_temp           | na          
 p0_core14_temp           | na          
 p0_core15_temp           | 37.000      
 p0_core16_temp           | na          
 p0_core17_temp           | 37.000      
 p0_core18_temp           | na          
 p0_core19_temp           | 39.000      
 p0_core20_temp           | na          
 p0_core21_temp           | 39.000      
 p0_core22_temp           | na          
 p0_core23_temp           | na          
 p0_vdd_temp              | 40.000 
 dimm0_temp               | 35.000      
 dimm1_temp               | na          
 dimm2_temp               | na          
 dimm3_temp               | na          
 dimm4_temp               | 38.000      
 dimm5_temp               | na          
 dimm6_temp               | na          
 dimm7_temp               | na          
 dimm8_temp               | na          
 dimm9_temp               | na          
 dimm10_temp              | na          
 dimm11_temp              | na          
 dimm12_temp              | na          
 dimm13_temp              | na          
 dimm14_temp              | na          
 dimm15_temp              | na          
 fan0                     | 1200.000    
 fan1                     | 1100.000    
 fan2                     | 1000.000    
 p0_power                 | 33.000      
 p0_vdd_power             | 5.000       
 p0_vdn_power             | 9.000       
 cpu_1_ambient            | 30.600      
 pcie                     | 27.000      
 ambient                  | 26.000  

You can see that I have 3 fans, two DIMMs (although why it lists 16 possible DIMMs for a two DIMM slot board is a good question!), and eight CPU cores. More on why the layout of the CPU cores is the way it is in a future post.

The code path for reading these sensors is interesting, it’s all from the BMC, so we’re having the OCC inside the P9 read things, which the BMC then reads, and then passes back to the P9. On the P9 itself, each sensor is a call all the way to firmware and back! In fact, we can look at it in perf:

$ sudo perf record -g ipmitool sensor
$ sudo perf report --no-children
“ipmitool sensors” perf report

What are the 0x300xxxxx addresses? They’re the OPAL firmware (i.e. skiboot). We can look up the symbols easily, as the firmware exposes them to the kernel, which then plonks it in sysfs:

[stewart@blackbird9 ~]$ sudo head /sys/firmware/opal/symbol_map 
[sudo] password for stewart: 
0000000000000000 R __builtin_kernel_end
0000000000000000 R __builtin_kernel_start
0000000000000000 T __head
0000000000000000 T _start
0000000000000010 T fdt_entry
00000000000000f0 t boot_sem
00000000000000f4 t boot_flag
00000000000000f8 T attn_trigger
00000000000000fc T hir_trigger
0000000000000100 t sreset_vector

So we can easily look up exactly where this is:

[stewart@blackbird9 ~]$ sudo grep '18e.. ' /sys/firmware/opal/symbol_map 
 0000000000018e20 t .__try_lock.isra.0
 0000000000018e68 t .add_lock_request

So we’re managing to spend a whole 12% of execution time spinning on a spinlock in firmware! The call stack of what’s going on in firmware isn’t so easy, but we can find the bt_add_ipmi_msg call there which is probably how everything starts:

[stewart@blackbird9 ~]$ sudo grep '516.. ' /sys/firmware/opal/symbol_map   0000000000051614 t .bt_add_ipmi_msg_head  0000000000051688 t .bt_add_ipmi_msg  00000000000516fc t .bt_poll

OCCTOOL

This is the most not-what-you’re-meant-to-use method of getting access to sensors! It’s using a debug tool for the OCC firmware! There’s a variety of tools in the OCC source repositiory, and one of them (occtoolp9) can be used for a variety of things, one of which is getting sensor data out of the OCC.

$ sudo ./occtoolp9 -SL
     Sensor Type: 0xFFFF
 Sensor Location: 0xFFFF
     (only displaying non-zero sensors)
 Sending 0x53 command to OCC0 (via opal-prd)…
   MFG Sub Cmd: 0x05  (List Sensors)
   Num Sensors: 50
     [ 1] GUID: 0x0000 / AMEintdur…….  Sample:     20  (0x0014)
     [ 2] GUID: 0x0001 / AMESSdur0…….  Sample:      7  (0x0007)
     [ 3] GUID: 0x0002 / AMESSdur1…….  Sample:      3  (0x0003)
     [ 4] GUID: 0x0003 / AMESSdur2…….  Sample:     23  (0x0017)

The odd thing you’ll see is “via opal-prd” – and this is because it’s doing raw calls to the opal-prd binary to talk to the OCC firmware running things like “opal-prd --expert-mode htmgt-passthru“. Yeah, this isn’t a in-production thing :)

Amazingly (and interestingly), this doesn’t go through host firmware in the way that an IPMI call will. There’s a full OCC/Host firmware interface spec to read. But it’s insanely inefficient way to monity sensors, a long bash script shelling out to a whole bunch of other processes… Think ~14.4 billion cycles versus ~367million cycles for the ipmitool option above.

But there are some interesting sensors at the end of the list:

Sensor Details: (found 86 sensors, details only for Status of 0x00)                                                  
     GUID Name             Sample     Min    Max U    Stat   Accum     UpdFreq   ScaleFactr   Loc   Type   
....
   0x014A MRDM0………..    688       3  15015 GBs  0x00 0x0144AE6C 0x00001901 0x000080FB 0x0008 0x0200
   0x014E MRDM4………..    480       3  14739 GBs  0x00 0x01190930 0x00001901 0x000080FB 0x0008 0x0200
   0x0156 MWRM0………..    560       4  16605 GBs  0x00 0x014C61FD 0x00001901 0x000080FB 0x0008 0x0200
   0x015A MWRM4………..    360       4  16597 GBs  0x00 0x014AE231 0x00001901 0x000080FB 0x0008 0x0200

is that memory bandwidth? Well, if I run the STREAM benchmark in a loop and look again:

0x014A MRDM0………..  15165       3  17994 GBs  0x00 0x0C133D6C 0x00001901 0x000080FB 0x0008 0x0200
   0x014E MRDM4………..  17145       3  18016 GBs  0x00 0x0BF501D6 0x00001901 0x000080FB 0x0008 0x0200
   0x0156 MWRM0………..   8063       4  24280 GBs  0x00 0x07C98B88 0x00001901 0x000080FB 0x0008 0x0200
   0x015A MWRM4………..   1138       4  24215 GBs  0x00 0x07CE82AF 0x00001901 0x000080FB 0x0008 0x0200

It looks like it! Are these exposed elsewhere? Well, another blog post at some point in the future is where I should look at that.

lm-sensors

$ rpm -qf /usr/bin/sensors
 lm_sensors-3.5.0-6.fc31.ppc64le

Ahhh, old faithful lm-sensors! Yep, a whole bunch of sensors are just exposed over the standard interface that we’ve been using since ISA was a thing.

[stewart@blackbird9 ~]$ sensors                                                                  
 ibmpowernv-isa-0000                                       
 Adapter: ISA adapter                                      
 Chip 0 Vdd Remote Sense:  +1.02 V  (lowest =  +0.72 V, highest =  +1.02 V)
 Chip 0 Vdn Remote Sense:  +0.67 V  (lowest =  +0.67 V, highest =  +0.67 V)
 Chip 0 Vdd:               +1.02 V  (lowest =  +0.73 V, highest =  +1.02 V)
 Chip 0 Vdn:               +0.68 V  (lowest =  +0.68 V, highest =  +0.68 V)
 Chip 0 Core 0:            +47.0°C  (lowest = +25.0°C, highest = +71.0°C)            
 Chip 0 Core 4:            +47.0°C  (lowest = +26.0°C, highest = +66.0°C)            
 Chip 0 Core 8:            +48.0°C  (lowest = +27.0°C, highest = +67.0°C)            
 Chip 0 Core 12:           +48.0°C  (lowest = +26.0°C, highest = +67.0°C)            
 Chip 0 Core 16:           +47.0°C  (lowest = +25.0°C, highest = +67.0°C)                      
 Chip 0 Core 20:           +47.0°C  (lowest = +26.0°C, highest = +69.0°C)            
 Chip 0 Core 24:           +48.0°C  (lowest = +27.0°C, highest = +67.0°C)                     
 Chip 0 Core 28:           +51.0°C  (lowest = +27.0°C, highest = +64.0°C)                     
 Chip 0 DIMM 0 :           +40.0°C  (lowest = +34.0°C, highest = +44.0°C)                     
 Chip 0 DIMM 1 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)                     
 Chip 0 DIMM 2 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 3 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 4 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 5 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 6 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 7 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 8 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 9 :            +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 10 :           +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 11 :           +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 12 :          +43.0°C  (lowest = +36.0°C, highest = +47.0°C)
 Chip 0 DIMM 13 :           +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 14 :           +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 DIMM 15 :           +0.0°C  (lowest =  +0.0°C, highest =  +0.0°C)
 Chip 0 Nest:              +48.0°C  (lowest = +27.0°C, highest = +64.0°C)
 Chip 0 VRM VDD:           +47.0°C  (lowest = +39.0°C, highest = +66.0°C)
 Chip 0 :                  44.00 W  (lowest =  31.00 W, highest = 132.00 W)
 Chip 0 Vdd:               15.00 W  (lowest =   4.00 W, highest = 104.00 W)
 Chip 0 Vdn:               10.00 W  (lowest =   8.00 W, highest =  12.00 W)
 Chip 0 :                 227.11 kJ
 Chip 0 Vdd:               44.80 kJ
 Chip 0 Vdn:               58.80 kJ
 Chip 0 Vdd:              +21.50 A  (lowest =  +6.50 A, highest = +104.75 A)
 Chip 0 Vdn:              +14.88 A  (lowest = +12.63 A, highest = +18.88 A)

The best thing? It’s really quick! The hwmon interface is fast and efficient.

Yet another near-upstream Raptor Blackbird firmware build

In what is coming a month occurance, I’ve put up yet another firmware build for the Raptor Blackbird with close-to-upstream firmware (see here and here for previous ones).

Well, I’ve done another build! It’s current op-build (as of yesterday), but my branch with patches for the Raptor Blackbird. The skiboot patch is there, the SBE speedup patch is now upstream. The machine-xml which is straight from Raptor but in my repo.

Here’s the current versions of everything:

$ lsprop /sys/firmware/devicetree/base/ibm,firmware-versions/
skiboot          "v6.5-228-g82aed17a-p4360f95"
bmc-firmware-version
                 "0.00"
occ              "3ab2921"
hostboot         "acdff8a-pe7e80e1"
buildroot        "2019.05.3-15-g3a4fc2a888"
capp-ucode       "p9-dd2-v4"
machine-xml      "site_local-stewart-a0efd66"
hostboot-binaries
                 "hw013120a.opmst"
sbe              "c318ab0-p1ddf83c"
hcode            "hw030220a.opmst"
petitboot        "v1.12"
phandle          0000064c (1612)
version          "blackbird-v2.4-514-g62d1a941"
linux            "5.4.22-openpower1-pdbbf8c8"
name             "ibm,firmware-versions"

If we compare this to the last build I put up, we have:

Componentoldnew
skibootv6.5-209-g179d53df-p4360f95v6.5-228-g82aed17a-p4360f95
linux5.4.13-openpower1-pa361bec5.4.22-openpower1-pdbbf8c8
occ3ab2921no change
hostboot779761d-pe7e80e1acdff8a-pe7e80e1
buildroot2019.05.3-14-g17f117295f2019.05.3-15-g3a4fc2a888
capp-ucodep9-dd2-v4no change
machine-xmlsite_local-stewart-a0efd66no change
hostboot-binarieshw011120a.opmsthw013120a.opmst
sbe166b70c-p06fc80cc318ab0-p1ddf83c
hcodehw011520a.opmsthw030220a.opmst
petitbootv1.11v1.12
versionblackbird-v2.4-415-gb63b36efblackbird-v2.4-514-g62d1a941

So, what do those changes mean? Not too much changed over the past month. Kernel bump, new petitboot (although I can’t find release notes but it doesn’t look like there’s a lot of changes), and slight bumps to other firmware components.

Grab blackbird.pnor from https://www.flamingspork.com/blackbird/stewart-blackbird-4-images/ and give it a whirl!

To flash it, copy blackbird.pnor to your Blackbird’s BMC in /tmp/ (important! the /tmp filesystem has enough room, the home directory for root does not), and then run:

pflash -E -p /tmp/blackbird.pnor

Which will ask you to confirm and then flash:

About to erase chip !
WARNING ! This will modify your HOST flash chip content !
Enter "yes" to confirm:yes
Erasing... (may take a while)
[==================================================] 99% ETA:1s      
done !
About to program "/tmp/blackbird.pnor" at 0x00000000..0x04000000 !
Programming & Verifying...
[==================================================] 100% ETA:0s   

Another close-to-upstream Blackbird Firmware Build

A few weeks ago (okay, close to six), I put up a firmware build for the Raptor Blackbird with close-to-upstream firmware (see here).

Well, I’ve done another build! It’s current op-build (as of this morning), but my branch with patches for the Raptor Blackbird. The skiboot patch is there, as is the SBE speedup patch. Current kernel (works fine with my hardware), current petitboot, and the machine-xml which is straight from Raptor but in my repo.

Versions of everything are:

$ lsprop /sys/firmware/devicetree/base/ibm,firmware-versions/
skiboot          "v6.5-209-g179d53df-p4360f95"
bmc-firmware-version
		 "0.01"
occ              "3ab2921"
hostboot         "779761d-pe7e80e1"
buildroot        "2019.05.3-14-g17f117295f"
capp-ucode       "p9-dd2-v4"
machine-xml      "site_local-stewart-a0efd66"
hostboot-binaries
		 "hw011120a.opmst"
sbe              "166b70c-p06fc80c"
hcode            "hw011520a.opmst"
petitboot        "v1.11"
phandle          000005d0 (1488)
version          "blackbird-v2.4-415-gb63b36ef"
linux            "5.4.13-openpower1-pa361bec"
name             "ibm,firmware-versions"

You can download all the bits (including debug tarball) from https://www.flamingspork.com/blackbird/stewart-blackbird-2-images/ and follow the instructions for trying it out or flashing blackbird.pnor.

Again, would love to hear how it goes for you!

Speeding up Blackbird boot: the SBE

The Self Boot Engine (SBE) is a small embedded PPE42 core inside the POWER9 CPU which has the unenvious job of getting a single POWER9 core ready enough to start executing instructions out of L3 cache, and poking some instructions into said cache for the core to start executing.

It’s called the “Self Boot Engine” as in generations prior to POWER8, it was the job of the FSP (Service Processor) to do all of the booting for the CPU. On POWER8, there was still an SBE, but it was a custom instruction set (this was the Power On Reset Engine – PORE), while the PPE42 is basically a 32bit powerpc core cut straight down the middle (just the way to make it awkward for toolchains).

One of the things I noted in my post on Booting temporary firmware on the Raptor Blackbird is that we got serial console output from the SBE. It turns out one of thing things explicitly not enabled by Raptor in their build was this output as “it made the SBE boot much slower”. I’d actually long suspected this, but hadn’t really had the time to delve into it.

Since for POWER9, the firmware for the SBE is now open source code, as is the ppe42-binutils and ppe42-gcc toolchain for it. This means we can hack on it!

WARNING: hacking on your SBE firmware can be relatively dangerous, as it’s literally the first thing that needs to work in order to boot the system, and there isn’t (AFAIK) publicly documented easy way to re-flash your SBE firmware if you mess it up.

Seeing as we saw a regression in boot time with the UART output enabled, we need to look at the uartPutChar() function in sbeConsole.C (error paths removed for clarity):

static void uartPutChar(char c)
{
    #define SBE_FUNC "uartPutChar"
    uint32_t rc = SBE_SEC_OPERATION_SUCCESSFUL;
    do {
        static const uint64_t DELAY_NS = 100;
        static const uint64_t DELAY_LOOPS = 100000000;

        uint64_t loops = 0;
        uint8_t data = 0;
        do {
            rc = readReg(LSR, data);
...
            if(data == LSR_BAD || (data & LSR_THRE))
            {
                break;
            }
            delay(DELAY_NS, 1000000);
        } while(++loops < DELAY_LOOPS);

...
        rc = writeReg(THR, c);
...
    } while(0);

    #undef SBE_FUNC
}

One thing you may notice if you’ve spent some time around serial ports is that it’s not using the transmit FIFO! While according to Wikipedia the original 16550 had a broken FIFO, but we’re certainly not going to be hooked up to an original rev of that silicon.

To compare, let’s look at the skiboot code, which is all in hw/lpc-uart.c:

static void uart_check_tx_room(void)
{
	if (uart_read(REG_LSR) & LSR_THRE) {
		/* FIFO is 16 entries */
		tx_room = 16;
		tx_full = false;
	}
}

The uart_check_tx_room() function is pretty simple, it checks if there’s room in the FIFO and knows that there’s 16 entries. Next, we have a busy loop that waits until there’s room again in the FIFO:

static void uart_wait_tx_room(void)
{
	while (!tx_room) {
		uart_check_tx_room();
		if (!tx_room) {
			smt_lowest();
			do {
				barrier();
				uart_check_tx_room();
			} while (!tx_room);
			smt_medium();
		}
	}
}

Finally, the bit of code that writes the (internal) log buffer out to a serial port:

/*
 * Internal console driver (output only)
 */
static size_t uart_con_write(const char *buf, size_t len)
{
	size_t written = 0;

	/* If LPC bus is bad, we just swallow data */
	if (!lpc_ok() && !mmio_uart_base)
		return written;

	lock(&uart_lock);
	while(written < len) {
		if (tx_room == 0) {
			uart_wait_tx_room();
			if (tx_room == 0)
				goto bail;
		} else {
			uart_write(REG_THR, buf[written++]);
			tx_room--;
		}
	}
 bail:
	unlock(&uart_lock);
	return written;
}

The skiboot code ends up being a bit more complicated thanks to a number of reasons, but the basic algorithm could be applied to the SBE code, and rather than busy waiting for each character to be written out before sending the other into the FIFO, we could just splat things down there and continue with life. So, I put together a patch to try out.

Before (i.e. upstream SBE code): it took about 15 seconds from “Welcome to SBE” to “Booting Hostboot”.

Now (with my patch): Around 10 seconds.

It’s a full five seconds (33%) faster to get through the SBE stage of booting. Wow.

Hopefully somebody looks at the pull request sometime soon, as it’s probably useful to a lot of people doing firmware and Operating System development.

So, Happy New Year for Blackbird owners (I’ll publish a build with this and other misc improvements “soon”).

A close-to-upstream firmware build for the Raptor Blackbird

UPDATE: A newer version is available here

It goes without saying that using this build is a At Your Own Risk and I make zero warranty. AFAIK it can’t physically destroy your system.

My GitHub op-build branch stewart-blackbird-v1 has all the changes built into this build (the VERSION displayed in firmware will be slightly weird as I did the tagging afterwards… this is not meant to be “howto release firmware to the public”). Follow op-build pull 3341 for the state of upstreaming everything.

Binaries are over at https://www.flamingspork.com/blackbird/stewart-blackbird-v1-images/ (see the git branch of op-build for source).

To flash it (temporarily), grab blackbird.pnor, get it to /tmp on your BMC and follow the instructions I posted the other day.

I’d be interested in any feedback on what does/does not work.

Are you Fans of the Blackbird? Speak up, I can’t hear you over the fan.

So, as of yesterday, I started running a pretty-close-to-upstream op-build host firmware stack on my Blackbird. Notable yak-shaving has included:

Apart from that, I was all happy as Larry. Except then I went into the room with the Blackbird in it an went “huh, that’s loud”, and since it was bedtime, I decided it could all wait until the morning.

It is now the morning. Checking fan speeds over IPMI, one fan stood out (fan2, sitting at 4300RPM). This was a bit of a surprise as what’s silkscreened on the board is that the rear case fan is hooked up to ‘fan2″, and if we had a “start from 0/1” mix up, it’d be the front case fan. I had just assumed it’d be maybe OCC firmware dying or something, but this wasn’t the case (I checked – thanks occtoolp9!)

After a bit of digging around, I worked out this mapping:

IPMI fan0Rear Case FanMotherboard Fan 2
IPMI fan1Front Case FanMotherboard Fan 3
IPMI fan2CPU FanMotherboard Fan 1

Which is about as surprising and confusing as you’d think.

After a bunch of digging around the Raptor ports of OpenBMC and Hostboot, it seems that the IPL Observer which is custom to Raptor controls if the BMC decides to do fan control or not.

You can get its view of the world from the BMC via the (incredibly user friendly) poking at DBus:

busctl get-property org.openbmc.status.IPL /org/openbmc/status/IPL org.openbmc.status.IPL current_status; busctl get-property org.openbmc.status.IPL /org/openbmc/status/IPL org.openbmc.status.IPL current_istep

Which if you just have the Hostboot patch in (like I first did) you end up with:

s "IPL_RUNNING"
s "21,3"

Which is where Hostboot exits the IPL process (as you see on the screen) and hands over to skiboot. But if you start digging through their op-build tree, you find that there’s a signal_linux_start_complete script which calls pnv-lpc to write two values to LPC ports 0x81 and 0x82. The pnv-lpc utility is the external/lpc/ binary from skiboot, and these two ports are the “extended lpc port 80h” state.

So, to get back fan control? First, build the lpc utility:

git clone git@github.com:open-power/skiboot.git
cd skiboot/external/lpc
make

and then poke the magic values of “IPL complete and linux running”:

$ sudo ./lpc io 0x81.b=254
[io] W 0x00000081.b=0xfe
$ sudo ./lpc io 0x82.b=254
[io] W 0x00000082.b=0xfe

You get a friendly beep, and then your fans return to sanity.

Of course, for that to work you need to have debugfs mounted, as this pokes OPAL debugfs to do direct LPC operations.

Next up: think of a smarter way to trigger that than “stewart runs it on the command line”. Also next up: work out the better way to determine that fan control should be on and patch the BMC.

Upstreaming Blackbird firmware (step 1: skiboot)

Now that I can actually boot the machine, I could test and send my patch upstream for Blackbird support in skiboot. One thing I noticed with the current firmware from Raptor is that the PCIe slot names were wrong. While a pretty minor point, it’s a bit funny that there’s only two slots and the names were wrong.

The PCIe slot names are used to call out the physical location of PCIe cards in the system, so if you, say, hit a bunch of errors, OS/firmware can say “It’s this card in the slot labeled BLAH on the board”.

With my patch, the slot table from skiboot is spat out looking like this:

[   64.296743001,5] PHB#0000:00:00.0 [ROOT] 1014 04c1 R:00 C:060400 B:01..ff SLOT=SLOT1 PCIE 4.0 X16 
 [   64.296875483,5] PHB#0001:00:00.0 [ROOT] 1014 04c1 R:00 C:060400 B:01..01 SLOT=SLOT2 PCIE 4.0 X8 
 [   64.297054197,5] PHB#0001:01:00.0 [EP  ] 8086 f1a8 R:03 C:010802 (  mass-storage) LOC_CODE=SLOT2 PCIE 4.0 X8
 [   64.297285067,5] PHB#0002:00:00.0 [ROOT] 1014 04c1 R:00 C:060400 B:01..01 SLOT=Builtin SATA 
 [   64.297411565,5] PHB#0002:01:00.0 [LGCY] 1b4b 9235 R:11 C:010601 (          sata) LOC_CODE=Builtin SATA
 [   64.297554540,5] PHB#0003:00:00.0 [ROOT] 1014 04c1 R:00 C:060400 B:01..01 SLOT=Builtin USB 
 [   64.297732049,5] PHB#0003:01:00.0 [EP  ] 104c 8241 R:02 C:0c0330 (      usb-xhci) LOC_CODE=Builtin USB
 [   64.297848624,5] PHB#0004:00:00.0 [ROOT] 1014 04c1 R:00 C:060400 B:01..01 SLOT=Builtin Ethernet 
 [   64.298026870,5] PHB#0004:01:00.0 [EP  ] 14e4 1657 R:01 C:020000 (      ethernet) LOC_CODE=Builtin Ethernet
 [   64.298212291,5] PHB#0004:01:00.1 [EP  ] 14e4 1657 R:01 C:020000 (      ethernet) LOC_CODE=Builtin Ethernet
 [   64.298424962,5] PHB#0004:01:00.2 [EP  ] 14e4 1657 R:01 C:020000 (      ethernet) LOC_CODE=Builtin Ethernet
 [   64.298587848,5] PHB#0005:00:00.0 [ROOT] 1014 04c1 R:00 C:060400 B:01..02 SLOT=BMC 
 [   64.298722540,5] PHB#0005:01:00.0 [ETOX] 1a03 1150 R:04 C:060400 B:02..02 LOC_CODE=BMC
 [   64.298850009,5] PHB#0005:02:00.0 [PCID] 1a03 2000 R:41 C:030000 (           vga) LOC_CODE=BMC

If you want to give it a go, grab the patch, build skiboot, and flash it on. Alternatively, you can download a built skiboot here. To flash it, do this:

# Copy to your BMC for the Blackbird
scp skiboot-v6.5-146-g376bed3f.lid.xz.stb root@blackbird:/tmp/

# then, ssh to the BMC
$ ssh root@blackbird

# ensure the machine is off
obmcutil poweroff --wait

# Now, make a backup copy (remember to copy it off /tmp on the bmc)
pflash -P PAYLOAD -r /tmp/skiboot-backup

# and flash the new skiboot:
pflash -e -P PAYLOAD -p /tmp/skiboot.lid.xz.stb

# now, power on the box
obmcutil poweron

Blackbird (singing in the dead of night..)

Way back when Raptor Computer Systems was doing pre-orders for the microATX Blackboard POWER9 system, I put in a pre-order. Since then, I’ve had a few life changes (such as moving to the US and starting to work for Amazon rather than IBM), but I’ve finally gone and done (most of) the setup for my own POWER9 system on (or under) my desk.

An 8 core POWER9 CPU, in bubble wrap and plastic packaging.

Everything came in a big brown box, all rather well packed. I had the board, CPU, heatsink assembly and the special tool to attach the heatsink to the board. Although unique to POWER9, the heatsink/fan assembly was one of the easier ones I’ve ever attached to a board.

The board itself looks pretty much as you’d expect – there’s a big spot for the CPU, a couple of PCI slots, a couple of DIMM slots and some SATA connectors.

The bits that are a bit unusual for a micro-ATX board are the big space reserved for FlexVer, the ASPEED BMC chip and the socketed flash. FlexVer is something I’m not ever going to use, and instead wish that there was an on-board m2 SSD slot instead, even if it was just PCIe. Having to sacrifice a PCIe slot just for a SSD is kind of a bummer.

The Blackbird POWER9 board
The POWER9 chip in socket

One annoying thing is my DIMMs are taking their sweet time in getting here, so I couldn’t actually populate the board with any memory.

Even without memory though, you can start powering it on and see that everything else works okay (i.e. it’s not completely boned). So, even without DIMMs, I could plug it in, and observe the Hostboot firmware complaining about insufficient hardware to IPL the box.

It Lives!

Yep, out the console (via ssh) you clearly see where things fail:

--== Welcome to Hostboot hostboot-3beba24/hbicore.bin ==--

  3.03104|secure|SecureROM valid - enabling functionality
  6.67619|Booting from SBE side 0 on master proc=00050000
  6.85100|ISTEP  6. 5 - host_init_fsi
  7.23753|ISTEP  6. 6 - host_set_ipl_parms
  7.71759|ISTEP  6. 7 - host_discover_targets
 11.34738|HWAS|PRESENT> Proc[05]=8000000000000000
 11.34739|HWAS|PRESENT> Core[07]=1511540000000000
 11.69077|ISTEP  6. 8 - host_update_master_tpm
 11.73787|SECURE|Security Access Bit> 0x0000000000000000
 11.73787|SECURE|Secure Mode Disable (via Jumper)> 0x8000000000000000
 11.76276|ISTEP  6. 9 - host_gard
 11.96654|HWAS|FUNCTIONAL> Proc[05]=8000000000000000
 11.96655|HWAS|FUNCTIONAL> Core[07]=1511540000000000
 12.07554|================================================
 12.07554|Error reported by hwas (0x0C00) PLID 0x90000007
 12.10289|  checkMinimumHardware found no functional dimm cards.
 12.10290|  ModuleId   0x03 MOD_CHECK_MIN_HW
 12.10291|  ReasonCode 0x0c06 RC_SYSAVAIL_NO_MEMORY_FUNC
 12.10292|  UserData1  HUID of node : 0x0002000000000000
 12.10293|  UserData2  number of present, non-functional dimms : 0x0000000000000000
 12.10294|------------------------------------------------
 12.10417|  Callout type             : Procedure Callout
 12.10417|  Procedure                : EPUB_PRC_FIND_DECONFIGURED_PART
 12.10418|  Priority                 : SRCI_PRIORITY_HIGH
 12.10419|------------------------------------------------
 12.10420|  Hostboot Build ID: hostboot-3beba24/hbicore.bin
 12.10421|================================================
 12.51718|================================================
 12.51719|Error reported by hwas (0x0C00) PLID 0x90000007
 12.51720|  Insufficient hardware to continue.
 12.51721|  ModuleId   0x03 MOD_CHECK_MIN_HW
 12.51722|  ReasonCode 0x0c04 RC_SYSAVAIL_INSUFFICIENT_HW
 12.54457|  UserData1   : 0x0000000000000000
 12.54458|  UserData2   : 0x0000000000000000
 12.54458|------------------------------------------------
 12.54459|  Callout type             : Procedure Callout
 12.54460|  Procedure                : EPUB_PRC_FIND_DECONFIGURED_PART
 12.54461|  Priority                 : SRCI_PRIORITY_HIGH
 12.54462|------------------------------------------------
 12.54462|  Hostboot Build ID: hostboot-3beba24/hbicore.bin
 12.54463|================================================
 12.73660|System shutting down with error status 0x90000007
 12.75545|================================================
 12.75546|Error reported by istep (0x1700) PLID 0x90000007
 12.77991|  IStep failed, see other log(s) with the same PLID for reason.
 12.77992|  ModuleId   0x01 MOD_REPORTING_ERROR
 12.77993|  ReasonCode 0x1703 RC_FAILURE
 12.77994|  UserData1  eid of first error : 0x9000000800000c04
 12.77995|  UserData2  Reason code of first error : 0x0000000100000609
 12.77996|------------------------------------------------
 12.77996|  host_gard
 12.77997|------------------------------------------------
 12.77998|  Callout type             : Procedure Callout
 12.77998|  Procedure                : EPUB_PRC_HB_CODE
 12.77999|  Priority                 : SRCI_PRIORITY_LOW
 12.78000|------------------------------------------------
 12.78001|  Hostboot Build ID: hostboot-3beba24/hbicore.bin
 12.78002|================================================

Looking forward to getting some DIMMs to show/share more.

Looking at the state of Blackbird firmware

Having been somewhat involved in OpenPOWER firmware, I have a bunch of experience and opinions on maintaining firmware trees for products, what working with upstream looks like and all that.

So, with my new Blackbird system I decided to take a bit of a look as to what the firmware situation was like.

There’s two main parts of firmware: BMC and Host. The BMC firmware runs purely on the ASPEED AST2500 and is based on OpenBMC while the host firmware is what runs on the POWER9 and is based off of OpenPOWER Firmware as assembled by op-build.

Initial impressions on the BMC is that there doesn’t seem to be any web based UI for it, which is kind of disappointing, as the Web UI being developed upstream has some nice qualities, and I’d say I even enjoyed using it when it was built into BMC firmware for systems we had when I was at IBM.

Looking at the git trees, the raptor-v1.00 tag is OpenBMC 2.7.0-dev-533-g386e5602e while current master is 2.8.0-dev-960-g10f7830bd. The spot where it split off was 2.7.0-dev-430-g7443ee80b, from April 2019 – so it’s not too old, but I’m also not convinced there should have been some security patches since then.

I’m not sure if any of the OpenBMC code is upstream, I haven’t looked.

Unfortunately, none of the host firmware is upstream.

On the host firmware side, v2.3-rc2-67-ga6a5f142 is the Raptor tag, and that compares with current master of v2.4-305-g54d8daf4, the place where Raptor forked was v2.3-rc2-9-g7b556015, again in April of 2019. Considering there was an upstream release in May of 2019 (v2.3), and again in July (v2.4), it could have easily have made it into an upstream release.

Unfortunately, there doesn’t seem to have been an upstream op-build release since v2.4 back in July (when I made it shortly before leaving IBM).

The skiboot component of host firmware has had an upstream release since I left (v6.5 in mid-August 2019), so the (rather trivial) platform support could have easily made it. I have a cleaned up and ready to upstream patch for it, I just need some DIMMs to actually test with before I send the patch.

As the current firmware situation stands, producing another build with updated upstream code is tricky due to the out-of-tree nature of the Blackbird patches, and a straight “git merge” is probably doable by some people, but not everybody.

On my TODO list is to get all the code into a state I can upstream it, assess vulnerability to CVE-2019-6260, and work out how I want to make it do Secure Boot (something that isn’t in upstream firmware yet, and currently would require a TPM, which I do not have).