Re: [PATCH] fix dir2 shortform structures on ARM old ABI

[Eric Sandeen <sandeen@sandeen.net>]

Timothy Shimmin wrote:
> David Chinner wrote:
>> On Fri, May 02, 2008 at 03:55:45PM -0500, Eric Sandeen wrote:
>>> Eric Sandeen wrote:
>>>> Eric Sandeen wrote:
>>>>> This should fix the longstanding issues with xfs and old ABI
>>>>> arm boxes, which lead to various asserts and xfs shutdowns,
>>>>> and for which an (incorrect) patch has been floating around
>>>>> for years.  (Said patch made ARM internally consistent, but
>>>>> altered the normal xfs on-disk format such that it looked
>>>>> corrupted on other architectures):
>>>>> http://lists.arm.linux.org.uk/lurker/message/20040311.002034.5ecf21a2.html
>>>> ping again...
>>> ping #3...
>> <sigh>
>>
>> Looks like if I don't pick it up then nobody is going to answer.
>> I'll run it through my ia64 and x86_64 test boxes and if it's ok
>> then I'll commit it.
>>
> As it only defines __arch_pack for __arm__,
> I literally can't see how on earth it won't pass for ia64 and x86-64,
> though I realise (I guess) we need to test to be sure :)
> 
> So Eric tested this on qemu-arm with success.
> And there was a little debate over whether ARM-EABI would work
> currently in XFS, 
> with Luca Olivetti saying in one kernel he has success and in another
> he doesn't. And Andre Draszik saying that for ARM-EABI it wouldn't
> work.

The patch should only affect behavior on *old* abi:

+#if defined(__arm__) && !defined(__ARM_EABI__)

it is the only one with the unique alignment that matters here.

There *is* still another issue on some arm chips related to processor
cache flushing; I didn't see the problem in qemu because it the emulator
does not have this behavior.

But, it's a separate issue from the structure alignment this patch
addresses.

One thing at a time. :)

Thanks,

-Eric

> That aside, Eric has tried out on ARM without EABI (old ABI) and has had success,
> so it is at least useful for this case.
> I don't see us doing any arm testing for this ourselves :)
> 
> --Tim
>