Bug#550562: Blob firmware loader corrupts filesystem
I now believe radeon_cp.c is not the problem. In fact, the radeon DRM
driver appears to be completely innocent. I'd appreciate any help or
suggestions where to look next.
Less short: Using alternate versions of radeon_cp.c and the entire
radeon driver directory to compile the radeon.ko kernel module, I was
still able to trigger the bug on Debian.
Verbose: I've been compiling kernel modules to see if I can
interpolate the point where the bug is triggered. I had been
suspecting drivers/gpu/drm/radeon/radeon_cp.c since that seemed to be
the most obvious change between the working and non-working drivers.
I now am 85% sure that radeon_cp.c is not the problem.¹
I copied Ubuntu's radeon_cp.c file (and the associated firmware .h) to
an otherwise pure Debian/testing box. When I compiled and installed
that kernel module the bug still occurred; that is, my filesystem was
corrupted.
Next I tried copying the entire driver/gpu/drm/radeon directory from
Ubuntu and compiled that kernel module under Debian. I was surprised
to find that the bug still manifested using that kernel module as
well.
I also attempted to force Ubuntu's precompiled radeon.ko to load but
didn't go any further than the error: Unknown symbol pv_lock_ops.
Summary:
Debian/stable (2.6.26): DRI works perfectly.
Ubuntu/karmic (2.6.31): DRI works perfectly
Debian/testing (2.6.32): DRI destroys file system
Debian/testing using karmic's radeon driver: DRI destroys file system
--Ben
__
¹ The 15% uncertainty is because I have only tested this a few times.
Occasionally the filesystem would become so corrupted it had to be
completely wiped and reinstalled, which makes for slow debugging.
On Tue, Jan 12, 2010 at 8:29 AM, Ben Hutchings <ben@decadent.org.uk> wrote:
> On Tue, 2010-01-12 at 04:30 -0800, Ben Wong wrote:
>> I have organized this bug report so that the most important information
>> is at the top so that you can stop reading as soon as you get bored.
>>
>> This bug, #550562, should be reclassified as a critical bug and possibly
>> merged with #560126.
>
> I think you're right.
>
>> This bug causes severe filesystem corruption and catastrophic loss of
>> data by scribbling on the hard drives. It is completely reproducible.
>> It seems to only affect systems that use the radeon/R200_cp.bin
>> firmware when it is separated from the kernel. (Could it be that the
>> binary blob didn't get copied correctly when it was split?)
>
> I've compared them again - they're identical to the blobs previously
> embedded in the driver (except for byteswapping).
>
> When you say it 'only affect systems that use the radeon/R200_cp.bin
> firmware' do you mean that you tested systems with other Radeon GPU
> versions and they were not affected, or that this problem appeared after
> the firmware was separated out (Debian package version 2.6.29-1)?
>
> Ben.
>
> --
> Ben Hutchings
> The generation of random numbers is too important to be left to chance.
> - Robert Coveyou
>
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