Saturday, February 27, 2010

sneak preview screenshots

I haven't posted any images in my blog yet, so it may be the time to fix it:

Solaris 2.6 and Solaris 7 are not very different. Up to 2.6 you can already make such screenshots yourself using the vanilla qemu (git/master). Sneak preview starts here:

For some reason, Solaris 9 looks not that nice:

For all the installations I used a 'PC console' terminal type. Maybe it's not recommended anymore? That's how it looked at the end:

And yes, instead of pressing Return to reboot the qemu machine, I still had to do the following:

echo set scsi_options=0x58 >> /a/etc/system

So, I've achieved the goal I set 7 moths ago. Solaris 9/SPARC will work under qemu.

Sunday, February 21, 2010

who is here?

How many people are reading my blog? I see ~ 30 page impressions daily, but I don't know how many of them are unique. Also it's possible that people read only the how-to, and not the rest. How many of you are actually reading this? Just leave a comment. If you do it anonymously, then please sign your message somehow, so  I can distinguish you (if there is more than one of  you :). It would be also interesting to know why are you reading this.

I see that this week there were suddenly two banner clicks! Who has clicked? I'd like to thank this people. Was there an interesting banner?

The question to the people who didn't click: are you annoyed by the ads here? I think about switching the banners off: after all 2 clicks within half a year is not a top business solution. Actually I'm also considering switching off this blog. Doesn't seem to be the right way for getting rich and famous.

Things I did for qemu/sparc weren't a rocket science. When I started a half year ago I didn't know neither the sparc assembly language, nor SPARCstation architecture, nor forth, nor qemu, nor git. Which means that I fixed all of this bugs just because I cared to fix them. Any other person who'd care would have fixed them too. Nobody else did, so probably no one actually needs emulating Solaris/sparc? Does any of you miss emulation of some other architecture/OS?

another week, another qemu bug again

Fixed one more CPU bug. Really surprised that it didn't affect Linux and Solaris versions prior 2.6. I'd expect that lots of multi-threaded code relying on mutex should have been affected...

Saturday, February 20, 2010

Lucky fix

It turned out that my last dma fixes had a nice side-effect: Solaris 8 and 9 don't complain about spurious timer interrupts anymore. I'm really surprised they don't because I'm absolutely sure there is at least one bug in the system timer. Funny enough fixing the timer bug without dma, covered 98% of spurious interrupt complains, whereas fixing dma removes 100% of them. After all it's possible that both documents describing the timer in two mutual exclusive ways describe it correctly. There are just multiple variants of the timer chip.

With the Solaris 7 hack, Solaris 8 & 9 can boot in a single user mode, regardless the timer fix. Will update the status in the how-to shortly.

Sunday, February 14, 2010

booting from a hdd image

For some reason during a HDD boot, SCSI disk driver (sd) is loaded before SCSI controller's (esp) . So the system can find no disks and exits causing kernel panic:

Cannot assemble drivers for root /iommu@0,10000000/sbus@0,10001000/espdma@5,8400000/esp@5,8800000/sd@0,0:a
Cannot mount root on /iommu@0,10000000/sbus@0,10001000/espdma@5,8400000/esp@5,8800000/sd@0,0:a fstype ufs
panic: vfs_mountroot: cannot mount root

A workaround: add the following line to /etc/system in the HDD image:
set scsi_options=0x58

Updated the Solaris/sparc under qemu how-to.

yet another dma bug

Fixed another bug in qemu sparc32 dma. This one seems to be only relevant for Linux guests though.

Sunday, February 7, 2010

another week, another qemu bug

There are very few qemu/sparc modules out there which I haven't had to touch. Since I've started I founded/fixed bugs in: irq, esp, cpuesp, esp, cpu, scsi-disk, cpuscsi-disk, fdd, tcx, mmu, slavio, mmu. Today this list is extended with (sparc32_)dma.

Fixed a bug in dma which produced spurious interrupts and incomplete reads/writes. Will submit the patch later on this week.

Monday, February 1, 2010

Spurious interrupts

Previously qemu dropped interrupts on disabling them. The real hardware doesn't do it. Which means, that lots of interrupts were dropped, including the spurious ones. But the real ones were dropped too, that's why the system timer was ticking so slow.

The question is where the spurious  IRQs are coming from: it's not only the ESP which produces them, under Solaris 8 & 9 there are lots of complains about spurious timer interrupts, and they both seem to crash due to a buffer overflow during processing of a (possibly spurious) LE interrupt.

NetBSD 1.3.3 boot doesn't crash with my wrong irq patch. The patch makes qemu drop interrupts, including the spurious ones.

All in all it looked like there is one global problem with interrupts processing. Until now. But now it looks like there is not one source of spurious interrupts, but many.
  • esp doesn't seem to produce spurious interrupts under Solaris while reading.
  • I've found a bug in the slavio timer which produces spurious interrupts.
  • NetBSD may be crashing due to another issue: I don't have a disk which I could boot under OBP. It is possible that OpenBIOS is not compatible with the older NetBSD versions. Update: This is the reason for NetBSD crashing, Michael Kostylev confirmed it.