Yearly Archives: 2016

Fast Reset, Trusted Boot and the security of /sbin/reboot

Posted on by
Reply

In OpenPOWER land, we’ve been doing some work on Secure and Trusted Boot while at the same time doing some work on what we call fast-reset (or fast-reboot, depending on exactly what mood someone was in at any particular time…. we should start being a bit more consistent).

The basic idea for fast-reset is that when the OS calls OPAL reboot, we gather all the threads in the system using a combination of patching the reset vector and soft-resetting them, then cleanup a few bits of hardware (we do re-probe PCIe for example), and reload & restart the bootloader (petitboot).

What this means is that typing “reboot” on the command line goes from a ~90-120+ second affair (through firmware to petitboot, linux distros still take ages to shut themselves down) down to about a 20 second affair (to petitboot).

If you’re running a (very) recent skiboot, you can enable it with a special hidden NVRAM configuration option (although we’ll likely enable it by default pretty soon, it’s proving remarkably solid). If you want to know what that NVRAM option is… Use the source, Luke! (or git history, but I’ve yet to see a neat Star Wars reference referring to git commit logs).

So, there’s nothing like a demo. Here’s a demo with Ubuntu running off an NVMe drive on an IBM S822LC for HPC (otherwise known as Minsky or Garrison) which was running the HTX hardware exerciser, through fast-reboot back into Petitboot and then booting into Ubuntu and auto-starting the exerciser (HTX) again.

Apart from being stupidly quick when compared to a full IPL (Initial Program Load – i.e. boot), since we’re not rebooting out of band, we have no way to reset the TPM, so if you’re measuring boot, each subsequent fast-reset will result in a different set of measurements.

This may be slightly confusing, but it’s not really a problem. You see, if a machine is compromised, there’s nothing stopping me replacing /sbin/reboot with something that just prints things to the console that look like your machine rebooted but in fact left my rootkit running. Indeed, fast-reset and a full IPL should measure different values in the TPM.

It also means that if you ever want to re-establish trust in your OS, never do a reboot from the host – always reboot out of band (e.g. from a BMC). This, of course, means you’re trusting your BMC to not be compromised, which I wouldn’t necessarily do if you suspect your host has been.

Windows NT4 for PowerPC guest on OPAL on POWER8 in qemu

Posted on by
4

Sometimes, programming is just for fun. This is what PREPHV is for Andrei Warkentin. To quote the README:

“This is mostly a huge ugly hack, derived from my
ppc64le_hello code. The running philosophy here is
to throw things together late at night with my family
asleep and see how far I get without a real design
or without a real desire to implement boring things
like IDE (*sigh*) emulation”

Since my day job is maintaining the firmware that it runs on, I decided to have a go (it also ties in with the retro stuff I’ve been blogging about). So…

screenshot-from-2016-10-30-17-22-20and I’m off! (yes, this is the very latest qemu and skiboot):

screenshot-from-2016-10-30-17-23-32screenshot-from-2016-10-30-17-23-48Yes, prephv does clear all thirty two megabytes of guest memory

screenshot-from-2016-10-30-17-24-15A quick diversion, if you try Windows NT 3.51 for PowerPC, you get this:

screenshot-from-2016-10-30-18-17-35

But on NT4, you continue unharmed:

screenshot-from-2016-10-30-17-22-32A sign I needed to hack my filesystem of bits of NT installer bits a bit more:

screenshot-from-2016-10-30-17-22-45But, on my next try:

screenshot-from-2016-10-30-17-25-26Well… looks like there’s an instruction that needs to be emulated (and there’s no code to currently do that). Mind you… this is decently far into booting before we hit anything fatal, which is a pretty impressive effort – and it is tempting to continue and see if it’ll run on real hardware and if it could be made to work well enough to not find any disks :)

Failed Retro emulation attempts

Posted on by
1

For reasons that should escape everybody, I went back and looked at some old Operating Systems a little while ago: OS/2 Warp, Windows 3.11 and Microsoft Chicago. So, I went on a little adventure this weekend, largely in failure though.

Windows NT 3.51

This was the first version (err… no, second I think) of Windows NT that I ever used.

Lesson 1: qemu doesn’t expose a SCSI adapter that isn’t virtio-scsi (and I have a feeling there aren’t Windows NT 3.51 installer driver floppies for virtio-scsi)

screenshot_winnt3-1_2016-10-29_191707Lesson 2: OMG I’m so glad I don’t have to wait for things to be read off floppy disks anymore:

screenshot_winnt3-51_2016-10-29_193833Lesson 3: I’d forgotten that the Windows directory on NT 3.51 was different to every other Windows NT version, being \WINNT35

screenshot_winnt3-51_2016-10-29_194040screenshot_winnt3-51_2016-10-29_194139Lesson 3: Yeah, sometimes there’s just fail.

screenshot_winnt3-51_2016-10-29_194147

Windows NT 4.0

This brought the UI of Windows 95 to Windows NT. It was a thing. It required a fairly beefy PC for the day, but it could use two CPUs if you were that amazingly rich (dual Pentium Pro was a thing)

Lesson 1: Windows NT 4 does not like 8GB disks. My idea of “creating a small disk for a VM for an old OS as it probably won’t work well with a 20GB disk” needs to be adjusted. I’m writing this on a system with 8 times more RAM than what I ended up using for a disk for Windows NT 4.

screenshot_winnt4-0_2016-10-29_192840But hey, back to \WINNT rather than \WINNT35 or \WINDOWS

screenshot_winnt4-0_2016-10-29_192937

Lesson 2: Sometimes, full system emulation turns out to be a better idea:

screenshot_winnt4-0_2016-10-29_192418screenshot_winnt4-0_2016-10-29_192304Lesson 3: Remember when Windows couldn’t actually format NTFS in the installer and it installed to FAT and then converted to NTFS? No? Well, aren’t you lucky.

screenshot_winnt4-0_2016-10-29_193102screenshot_winnt4-0_2016-10-29_193235Apple Rhapsody DR2

Before there was MacOS X, there was a project called Rhapsody. This was to take NeXTStep (from NeXT, which Apple bought to get both NeXTStep and Steve Jobs as every internal “let’s replace the aging MacOS” project had utterly failed for the past ten years). Rhapsody was not going to be backwards compatible until everybody said that was a terrible idea and the Blue Box was added (known as Classic) – basically, a para-virtualized VM running the old MacOS 9.

Anyway, for the first two developer releases, it was also available on x86 (not just PowerPC). This was probably because a PowerPC port to Macs was a lot newer than the x86 port.

So, I dusted off the (virtual) Boot and Driver floppies and fired up qemu…..

screenshot_rhapsodydr2_2016-10-29_172732Yeah, MacOS X got a better installer…

screenshot_rhapsodydr2_2016-10-29_173227Hopeful!

screenshot_rhapsodydr2_2016-10-29_182218This was after I decided that using KVM was a bad Idea:

screenshot_rhapsodydr2_2016-10-29_172143

screenshot_rhapsodydr2_2016-10-29_173333Nope… and this is where we stop. There seems to be some issue with ATA drivers? I honestly can’t be bothered to debug it (although… for the PowerPC version… maybe).

MacOS 9.2

Well.. this goes a lot better now thanks to a whole bunch of patches hitting upstream Qemu recently (thanks Ben!)

screenshot-from-2016-10-29-20-37-24screenshot-from-2016-10-29-20-42-10Yeah, I was kind of tempted to set up Outlook Express to read my email…. But running MacOS 9 was way too successful, so I had to stop there :)

Workaround for opal-prd using 100% CPU

Posted on by
Reply

opal-prd is the Processor RunTime Diagnostics daemon, the userspace process that on OpenPower systems is responsible for some of the runtime diagnostics. Although a userspace process, it memory maps (as in mmap) in some code loaded by early firmware (Hostboot) called the HostBoot RunTime (HBRT) and runs it, using calls to the kernel to accomplish any needed operations (e.g. reading/writing registers inside the chip). Running this in user space gives us benefits such as being able to attach gdb, recover from segfaults etc.

The reason this code is shipped as part of firmware rather than as an OS package is that it is very system specific, and it would be a giant pain to update a package in every Linux distribution every time a new chip or machine was introduced.

Anyway, there’s a bug in the HBRT code that means if there’s an ECC error in the HBEL (HostBoot Error Log) partition in the system flash (“bios” or “pnor”… the flash where your system firmware lives), the opal-prd process may get stuck chewing up 100% CPU and not doing anything useful. There’s https://github.com/open-power/hostboot/issues/67 for this.

You will notice a problem if the opal-prd process is using 100% CPU and the last log messages are something like:

HBRT: ERRL:>>ErrlManager::ErrlManager constructor.
HBRT: ERRL:iv_hiddenErrorLogsEnable = 0x0
HBRT: ERRL:>>setupPnorInfo
HBRT: PNOR:>>RtPnor::getSectionInfo
HBRT: PNOR:>>RtPnor::readFromDevice: i_offset=0x0, i_procId=0 sec=11 size=0x20000 ecc=1
HBRT: PNOR:RtPnor::readFromDevice: removing ECC...
HBRT: PNOR:RtPnor::readFromDevice> Uncorrectable ECC error : chip=0,offset=0x0

(the parameters to readFromDevice may differ)

Luckily, there’s a simple workaround to fix it all up! You will need the pflash utility. Primarily, pflash is meant only for developers and those who know what they’re doing. You can turn your computer into a brick using it.

pflash is packaged in Ubuntu 16.10 and RHEL 7.3, but you can otherwise build it from source easily enough:

git clone https://github.com/open-power/skiboot.git
cd skiboot/external/pflash
make

Now that you have pflash, you just need to erase the HBEL partition and write (ECC) zeros:

dd if=/dev/zero of=/tmp/hbel bs=1 count=147456
pflash -P HBEL -e
pflash -P HBEL -p /tmp/hbel

Note: you cannot just erase the partition or use the pflash option to do an ECC erase, you may render your system unbootable if you get it wrong.

After that, restart opal-prd however your distro handles restarting daemons (e.g. systemctl restart opal-prd.service) and all should be well.

MySQL removes the FRM (7 years after Drizzle did)

Posted on by
9

The new MySQL 8.0.0 milestone release that was recently announced brings something that has been a looooong time coming: the removal of the FRM file. I was the one who implemented this in Drizzle way back in 2009 (July 28th 2009 according to Brian)- and I may have had a flashback to removing the tentacles of the FRM when reading the MySQL 8.0.0 announcement.

As an idea for how long this has been on the cards, I’ll quote Brian from when we removed it in Drizzle:

We have been talking about getting rid of FRM since around 2003. I remember a drive up to northern Finland with Kaj Arnö, where we spent an hour talking about this. I, David, and MontyW have talked about this for years.

http://krow.livejournal.com/642329.html

Soo… it was a known problem for at least thirteen years. One of the issues removing it was how pervasive all of the FRM related things were. I shudder at the mention of “pack_flag” and Jay Pipes probably does too.

At the time, we tried a couple of approaches as to how things should look. Our philosophy with Drizzle was that it should get out of the way at let the storage engines be the storage engines and not try to second guess them or keep track of things behind their back. I still think that was the correct architectural approach: the role of Drizzle was to put SQL on top of a storage engine, not to also be one itself.

Looking at the MySQL code, there’s one giant commit 31350e8ab15179acab5197fa29d12686b1efd6ef. I do mean giant too, the diffstat is amazing:

 786 files changed, 58471 insertions(+), 25586 deletions(-)

How anyone even remotely did code review on that I have absolutely no idea. I know the only way I could get it to work in Drizzle was to do it incrementally, a series of patches that gradually chiseled out what needed to be taken out so I could put it an API and the protobuf code.

Oh, and in case you’re wondering:

- uint offset,pack_flag;
+ uint offset;

Thank goodness. Now, you may not appreciate that as much as I might, but pack_flag was not the height of design, it was… pretty much a catchalll for some kind of data about a field that wasn’t something that already had a field in the FRM. So it may include information on if the field could be null or not, if it’s decimal, how many bytes an integer takes, that it’s a number and how many oh, just don’t ask.

Also gone is the weird interval_id and a whole bunch of limitations because of the FRM format, including one that I either just discovered or didn’t remember: if you used all 256 characters in an enum, you couldn’t create the table as MySQL would pick either a comma or an unused character to be the separator in the FRM!?!

Also changed is how the MySQL server handles default values. For those not aware, the FRM file contains a static copy of the row containing default values. This means the default values are computed once on table creation and never again (there’s a bunch of work arounds for things like AUTO_INCREMENT and DEFAULT NOW()). The new sql/default_values.cc is where this is done now.

For now at least, table metadata is also written to a file that appears to be JSON format. It’s interesting that a SQL database server is using a schemaless file format to describe schema. It appears that these files exist only for disaster recovery or perhaps portable tablespaces. As such, I’m not entirely convinced they’re needed…. it’s just a thing to get out of sync with what the storage engine thinks and causes extra IO on DDL (as well as forcing the issue that you can’t have MVCC into the data dictionary itself).

What will be interesting is to see the lifting of these various limitations and how MariaDB will cope with that. Basically, unless they switch, we’re going to see some interesting divergence in what you can do in either database.

There’s certainly differences in how MySQL removed the FRM file to the way we did it in Drizzle. Hopefully some of the ideas we had were helpful in coming up with this different approach, as well as an extra seven years of in-production use.

At some point I’ll write something up as to the fate of Drizzle and a bit of a post-mortem, I think I may have finally worked out what I want to say…. but that is a post for another day.

First look at MySQL 8.0.0 Milestone

Posted on by
1

So, about ten days ago the MySQL Server Team released MySQL 8.0.0 Milestone to the world. One of the most unfortunate things about MySQL development is that it’s done behind closed doors, with the only hints of what’s to come arriving in maybe a note on a bug or such milestone releases that contain a lot of code changes. How much code change? Well, according to the text up on github for the 8.0 branch “This branch is 5714 commits ahead, 4 commits behind 5.7. ”

Way back in 2013, I looked at MySQL Code Size over releases, which I can again revisit and include both MySQL 5.7 and 8.0.0.

While 5.7 was a big jump again, we seem to be somewhat leveling off, which is a good thing. Managing to add features and fix long standing problems without bloating code size is good for software maintenance. Honestly, hats off to the MySQL team for keeping it to around a 130kLOC code size increase over 5.7 (that’s around 5%).

These days I’m mostly just a user of MySQL, pointing others in the right direction when it comes to some issues around it and being the resident MySQL grey(ing)beard(well, if I don’t shave for a few days) inside IBM as a very much side project to my day job of OPAL firmware.

So, personally, I’m thrilled about no more FRM, better Unicode, SET PERSIST and performance work. With my IBM hat on, I’m thrilled about the fact that it compiled on POWER out of the box and managed to work (I haven’t managed to crash it yet). There seems to be a possible performance issue, but hey, this is a huge improvement over the 5.7 developer milestones when run on POWER.

A lot of the changes are focused around usability, making it easier to manage and easier to run at at least a medium amount of scale. This is long overdue and it’s great to see even seemingly trivial things like SET PERSIST coming (I cannot tell you how many times that has tripped me up).

In a future post, I’ll talk about the FRM removal!

Lesson 124 in why scales on a graph matter…

Posted on by
Reply

The original article presented two graphs: one of MariaDB searches (which are increasing) and the other showing MySQL searches (decreasing or leveling out). It turns out that the y axis REALLY matters.

I honestly expected better….

Compiling your own firmware for Barreleye (OpenCompute OpenPOWER system)

Posted on by
1

Aaron Sullivan announced on the Rackspace Blog that you can now get your own Barreleye system! What’s great is that the code for the Barreleye platform is upstream in the op-build project, which means you can build your own firmware for them (just like garrison, the “IBM S822LC for HPC” system I blogged about a few days ago).

Remarkably, to build an image for the host firmware, it’s eerily similar to any other platform:

git clone --recursive https://github.com/open-power/op-build.git
cd op-build
. op-build-env
op-build barreleye_defconfig
op-build

…and then you wait. You can cross compile on x86.

You’ve been able to build firmware for these machines with upstream code since Feb/March (I wouldn’t recommend running with builds from then though, try the latest release instead).

Hopefully, someone involved in OpenBMC can write on how to build the BMC firmware.

Compiling your own firmware for the S822LC for HPC

Posted on by
Reply

IBM (my employer) recently announced  the new S822LC for HPC POWER8+NVLINK NVIDIA P100 GPUs server (press release, IBM Systems Blog, The Register). The “For HPC” suffix on the model number is significant, as the S822LC is a different machine. What makes the “for HPC” variant different is that the POWER8 CPU has (in addition to PCIe), logic for NVLink to connect the CPU to NVIDIA GPUs.

There’s also the NVIDIA Tesla P100 GPUs which are NVIDIA’s latest in an SXM2 form factor, but instead of delving into GPUs, I’m going to tell you how to compile the firmware for this machine.

You see, this is an OpenPOWER machine. It’s an OpenPOWER machine where the vendor (in this case IBM) has worked to get all the needed code upstream, so you can see exactly what goes into a firmware build.

To build the latest host firmware (you can cross compile on x86 as we use buildroot to build a cross compiler):

git clone --recursive https://github.com/open-power/op-build.git
cd op-build
. op-build-env
op-build garrison_defconfig
op-build

That’s it! Give it a while and you’ll end up with output/images/garrison.pnor – which is a firmware image to flash onto PNOR. The machine name is garrison as that’s the code name for the “S822LC for HPC” (you may see Minsky in the press, but that’s a rather new code name, Garrison has been around for a lot longer as a name).

Microsoft Chicago – retro in qemu!

Posted on by
1

So, way back when (sometime in the early 1990s) there was Windows 3.11 and times were… for Workgroups. There was this Windows NT thing, this OS/2 thing and something brewing at Microsoft to attempt to make the PC less… well, bloody awful for a user.

Again, thanks to abandonware sites, it’s possible now to try out very early builds of Microsoft Chicago – what would become Windows 95. With the earliest build I could find (build 56), I set to work. The installer worked from an existing Windows 3.11 install.

I ended up using full system emulation rather than normal qemu later on, as things, well, booted in full emulation and didn’t otherwise (I was building from qemu master… so it could have actually been a bug fix).

chicago-launch-setupMmmm… Windows 3.11 File Manager, the fact that I can still use this is a testament to something, possibly too much time with Windows 3.11.

chicago-welcome-setupchicago-setupUnfortunately, I didn’t have the Plus Pack components (remember Microsoft Plus! ?- yes, the exclamation mark was part of the product, it was the 1990s.) and I’m not sure if they even would have existed back then (but the installer did ask).

chicago-install-dirObviously if you were testing Chicago, you probably did not want to upgrade your working Windows install if this was a computer you at all cared about. I installed into C:\CHICAGO because, well – how could I not!

chicago-installingThe installation went fairly quickly – after all, this isn’t a real 386 PC and it doesn’t have of-the-era disks – everything was likely just in the linux page cache.

chicago-install-networkI didn’t really try to get network going, it may not have been fully baked in this build, or maybe just not really baked in this copy of it, but the installer there looks a bit familiar, but not like the Windows 95 one – maybe more like NT 3.1/3.51 ?

But at the end… it installed and it was time to reboot into Chicago:
chicago-bootSo… this is what Windows 95 looked like during development back in July 1993 – nearly exactly two years before release. There’s some Windows logos that appear/disappear around the place, which are arguably much cooler than the eventual Windows 95 boot screen animation. The first boot experience was kind of interesting too:
Screenshot from 2016-08-07 20-57-00Luckily, there was nothing restricting the beta site ID or anything. I just entered the number 1, and was then told it needed to be 6 digits – so beta site ID 123456 it is! The desktop is obviously different both from Windows 3.x and what ended up in Windows 95.

Screenshot from 2016-08-07 20-57-48Those who remember Windows 3.1 may remember Dr Watson as an actual thing you could run, but it was part of the whole diagnostics infrastructure in Windows, and here (as you can see), it runs by default. More odd is the “Switch To Chicago” task (which does nothing if opened) and “Tracker”. My guess is that the “Switch to Chicago” is the product of some internal thing for launching the new UI. I have no ideawhat the “Tracker” is, but I think I found a clue in the “Find File” app:

Screenshot from 2016-08-13 14-10-10Not only can you search with regular expressions, but there’s “Containing text”, could it be indexing? No, it totally isn’t. It’s all about tracking/reporting problems:

Screenshot from 2016-08-13 14-15-19Well, that wasn’t as exciting as I was hoping for (after all, weren’t there interesting database like file systems being researched at Microsoft in the early 1990s?). It’s about here I should show the obligatory About box:
Screenshot from 2016-08-07 20-58-10It’s… not polished, and there’s certainly that feel throughout the OS, it’s not yet polished – and two years from release: that’s likely fair enough. Speaking of not perfect:

Screenshot from 2016-08-07 20-59-03When something does crash, it asks you to describe what went wrong, i.e. provide a Clue for Dr. Watson:

Screenshot from 2016-08-13 12-09-22

But, most importantly, Solitaire is present! You can browse the Programs folder and head into Games and play it! One odd tihng is that applications have two >> at the end, and there’s a “Parent Folder” entry too.

Screenshot from 2016-08-13 12-01-24Solitair itself? Just as I remember.

Screenshot from 2016-08-07 21-21-27Notably, what is missing is anything like the Start menu, which is probably the key UI element introduced in Windows 95 that’s still with us today. Instead, you have this:

Screenshot from 2016-08-13 11-55-15That’s about the least exciting Windows menu possible. There’s the eye menu too, which is this:

Screenshot from 2016-08-13 11-56-12More unfinished things are found in the “File cabinet”, such as properties for anything:
Screenshot from 2016-08-13 12-02-00But let’s jump into Control Panels, which I managed to get to by heading to C:\CHICAGO\Control.sys – which isn’t exactly obvious, but I think you can find it through Programs as well.Screenshot from 2016-08-13 12-02-41Screenshot from 2016-08-13 12-05-40The “Window Metrics” application is really interesting! It’s obvious that the UI was not solidified yet, that there was a lot of experimenting to do. This application lets you change all sorts of things about the UI:

Screenshot from 2016-08-13 12-05-57My guess is that this was used a lot internally to twiddle things to see what worked well.

Another unfinished thing? That familiar Properties for My Computer, which is actually “Advanced System Features” in the control panel, and from the [Sample Information] at the bottom left, it looks like we may not be getting information about the machine it’s running on.

Screenshot from 2016-08-13 12-06-39

You do get some information in the System control panel, but a lot of it is unfinished. It seems as if Microsoft was experimenting with a few ways to express information and modify settings.

Screenshot from 2016-08-13 12-07-13But check out this awesome picture of a hard disk for Virtual Memory:

Screenshot from 2016-08-13 12-07-47The presence of the 386 Enhanced control panel shows how close this build still was to Windows 3.1:

Screenshot from 2016-08-13 12-08-08At the same time, we see hints of things going 32 bit – check out the fact that we have both Clock and Clock32! Notepad, in its transition to 32bit, even dropped the pad and is just Note32!

Screenshot from 2016-08-13 12-11-10Well, that’s enough for today, time to shut down the machine:
Screenshot from 2016-08-13 12-15-45

Windows 3.11 nostalgia

Posted on by
4

Because OS/2 didn’t go so well… let’s try something I’m a lot more familiar with. To be honest, the last time I in earnest used Windows on the desktop was around 3.11, so I kind of know it back to front (fun fact: I’ve read the entire Windows 3.0 manual).

It turns out that once you have MS-DOS installed in qemu, installing Windows 3.11 is trivial. I didn’t even change any settings for Qemu, I just basically specced everything up to be very minimal (50MB RAM, 512mb disk).

win31-setupwin31-disk4win31-installedWindows 3.11 was not a fun time as soon as you had to do anything… nightmares of drivers, CONFIG.SYS and AUTOEXEC.BAT plague my mind. But hey, it’s damn fast on a modern processor.

OS/2 Warp Nostalgia

Posted on by
5

Thanks to the joys of abandonware websites, you can play with some interesting things from the 1990s and before. One of those things is OS/2 Warp. Now, I had a go at OS/2 sometime in the 1990s after being warned by a friend that it was “pretty much impossible” to get networking going. My experience of OS/2 then was not revolutionary… It was, well, something else on a PC that wasn’t that exciting and didn’t really add a huge amount over Windows.

Now, I’m nowhere near insane enough to try this on my actual computer, and I’ve managed to not accumulate any ancient PCs….

Luckily, qemu helps with an emulator! If you don’t set your CPU to Pentium (or possibly something one or two generations newer) then things don’t go well. Neither does a disk that by today’s standards would be considered beyond tiny. Also, if you dare to try to use an unpartitioned hard disk – OH MY are you in trouble.

Also, try to boot off “Disk 1” and you get this:
os2-wrong-floppyPossibly the most friendly error message ever! But, once you get going (by booting the Installation floppy)… you get to see this:

Screenshot from 2016-08-07 19-12-19and indeed, you are doing the time warp of Operating Systems right here. After a bit of fun, you end up in FDISK:

os2-installos2-1gb-too-muchWhy I can’t create a partition… WHO KNOWS. But, I tried again with a 750MB disk that already had a partition on it and…. FAIL. I think this one was due to partition type, so I tried again with partition type of 6 – plain FAT16, and not W95 FAT16 (LBA). Some memory is coming back to me of larger drives and LBA and nightmares…

But that worked!

warp4-installingos2-checkingThen, the OS/2 WARP boot screen… which seems to stick around for a long time…..

os2-install-2and maybe I could get networking….

os2-networkLadies and Gentlemen, the wonders of having to select DHCP:

os2-dhcpIt still asked me for some config, but I gleefully ignored it (because that must be safe, right!?) and then I needed to select a network adapter! Due to a poor choice on my part, I started with a rtl8139, which is conspicuously absent from this fine list of Token Ring adapters:

os2-tokenringand then, more installing……

os2-more-installingbefore finally rebooting into….

os2-failand that, is where I realized there was beer in the fridge and that was going to be a lot more fun.

Using Smatch static analysis on OpenPOWER OPAL firmware

Posted on by
2

For Skiboot, I’m always looking at new automated systems to find bugs in the code. A little while ago, I read about the Smatch tool developed by some folks at Oracle (they also wrote about using it on the Linux kernel).

I was eager to try it with skiboot to see if it could find anything.

Luckily, it was pretty easy. I built Smatch according to their documentation and then built skiboot:

make CHECK="/home/stewart/smatch/smatch" C=1 -j20 all check

Due to some differences in how we implement abort() and assert() in skiboot, I added “_abort”, “abort” and “assert_fail” to smatch_data/no_return_funcs in the Smatch source tree to silence some false positives.

It seems that there’s a few useful warnings there (some of which I’ve fixed in skiboot master already), along with some false positives around the preprocessor/complier tricks we do to ensure at compile time that an OPAL call definition has the correct number of arguments specified.

So far, so good though. Try it on your project!

Building OPAL firmware for POWER9

Posted on by
5

Recently, we merged into the op-build project (the build scripts for OpenPOWER Firmware) a defconfig for building OPAL for (certain) POWER9 simulators. I won’t bother linking over to articles on the POWER9 chip or schedule (there’s search engines for that), but with this commit – if you happen to be able to get your hands on a POWER9 simulator, you can now boot to the petitboot bootloader on it!

We’re using upstream Linux 4.7.0-rc3 and upstream skiboot (master), so all of this code is already upstream!

Now, by no means is this complete. There’s some fairly fundamental things that are missing (e.g. PCI) – but how many other platforms can you build open source firmware for before you can even get your hands on a simulator?

Fuzzing Firmware – afl-fuzz + skiboot

Posted on by
2

In what is likely to be a series on how firmware makes some normal tools harder to use, first I’m going to look at american fuzzy lop – a tool for fuzz testing that if you’re not using then you most certainly have bugs it’ll find for you.

I first got interested in afl-fuzz during Erik de Castro Lopo’s excellent linux.conf.au 2016 in Geelong earlier this year: “Fuzz all the things!“. In a previous life, the Random Query Generator managed to find a heck of a lot of bugs in MySQL (and Drizzle). For randgen info, see Philip Stoev’s talk on it from way back in 2009, a recent (2014) blog post on how Tokutek uses it and some notes on how it was being used at Oracle from 2013. Basically, the randgen was a specialized fuzzer that (given a grammar) would randomly generate SQL queries, and then (if the server didn’t crash), compare the result to some other database server (e.g. your previous version).

The afl-fuzz fuzzer takes a different approach – it’s a much more generic fuzzer rather than a targeted tool. Also, while tools such as the random query generator are extremely powerful and find specialized bugs, they’re hard to get started with. A huge benefit of afl-fuzz is that it’s really, really simple to get started with.

Basically, if you have a binary that takes input on stdin or as a (relatively small) file, afl-fuzz will just work and find bugs for you – read the Quick Start Guide and you’ll be finding bugs in no time!

For firmware of course, we’re a little different than a simple command line program as, well, we aren’t one! Luckily though, we have unit tests. These are just standard binaries that include a bunch of firmware code and get run in user space as part of “make check”. Also, just like unit tests for any project, people do send me patches that break tests (which I reject).

Some of these tests act on data we get from a place – maybe reading other parts of firmware off PNOR or interacting with data structures we get from other bits of firmware. For testing this code, it can be relatively easy to (for the test), read these off disk.

For skiboot, there’s a data structure we get from the service processor on FSP machines called HDAT. Basically, it’s just like the device tree, but different. Because yet another binary format is always a good idea (yes, that is laced with a heavy dose of sarcasm). One of the steps in early boot is to parse the HDAT data structure and convert it to a device tree. Luckily, we structured our code so that creating a unit test that can run in userspace was relatively easy, we just needed to dump this data structure out from a running machine. You can see the test case here. Basically, hdat_to_dt is a binary that reads the HDAT structure out of a pair of files and prints out a device tree. One of the regression tests we have is that we always produce the same output from the same input.

So… throwing that into AFL yielded a couple of pretty simple bugs, especially around aborting out on invalid data (it’s better to exit the process with failure rather than hit an assert). Nothing too interesting here on my simple input file, but it does mean that our parsing code exits “gracefully” on invalid data.

Another utility we have is actually a userspace utility for accessing the gard records in the flash. A GARD record is a record of a piece of hardware that has been deconfigured due to a fault (or a suspected fault). Usually this utility operates on PNOR flash through /dev/mtd – but really what it’s doing is talking to the libflash library, that we also use inside skiboot (and on OpenBMC) to read/write from flash directly, via /dev/mtd or just from a file. The good news? I haven’t been able to crash this utility yet!

So I modified the pflash utility to read from a file to attempt to fuzz the partition reading code we have for the partitioning format that’s on PNOR. So far, no crashes – although to even get it going I did have to fix a bug in the file handling code in pflash, so that’s already a win!

But crashing bugs aren’t the only type of bugs – afl-fuzz has exposed several cases where we act on uninitialized data. How? Well, we run some test cases under valgrind! This is the joy of user space unit tests for firmware – valgrind becomes a tool that you can run! Unfortunately, these bugs have been sitting in my “todo” pile (which is, of course, incredibly long).

Where to next? Fuzzing the firmware calls themselves would be nice – although that’s going to require a targeted tool that knows about what to pass each of the calls. Another round of afl-fuzz running would also be good, I’ve fixed a bunch of the simple things and having a better set of starting input files would be great (and likely expose more bugs).

First POWER9 bits merged into skiboot master

Posted on by
6

I just merged in some base POWER9 support patches into skiboot. While this is in no way near complete or really enough to be interesting to anyone that isn’t heavily involved in POWER9 development, it’s nice to take upstream first and open source first so seriously that this level of base enablement patches is easy to merge in.

Other work that has gone on for POWER9 in open source projects include way back in November 2015 where work for the updated PowerISA 3.0 was merged into binutils and this year there’s been kernel work too.

Video of my Percona Live Talk: Why would I run MySQL/MariaDB on POWER anyway?

Posted on by
9

Good news everyone! There’s video up for the talk I gave at Percona Live in April 2016 up: Why would I run MySQL/MariaDB on POWER anyway?

The talk is a general overview of POWER and why MySQL/MariaDB may be a good fit.

OpenPOWER, OpenCompute and fostering a firmware development community

Posted on by
2

Recently, I was at the OpenPOWER Summit in San Jose where people could see the Barreleye server (specs and design here, initial Rackspace blog post here). Barreleye is an OpenCompute form factor POWER8 server. It’s not only an OpenPOWER machine, which means all of the host firmware is free and open source software, but there’s also OpenBMC meaning that the source to the OS and userspace running on the BMC (service processor) is also open!

In addition, the firmware enablement came from Foxconn (see this skiboot commit), which means we’re being successful in enabling people who aren’t part of IBM to join the development community for OpenPOWER firmware and get the changes needed to support their machines accepted upstream.

Granted, the size of a firmware development community is always likely to be relatively small, but I really like how Foxconn has shown leadership to other ODMs on interacting with and becoming part of the OpenPOWER firmware community.

“Toy” database on mainframes

Posted on by
10

While much less common than 10 or 15 (err… even 20) years ago, you still sometimes hear MySQL being called a “toy” database. The good news is, when somebody says that, they’re admitting ignorance and you can help educate them!

Recently, a fellow IBMer submitted a pull request (and bug) to start having MySQL support on Z Series (s390x).

Generally speaking, when there’s effort being spent on getting something to run on Z, it is in no way considered a toy by those who’ll end up using it.