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

[Mark Goodwin <markgw@sgi.com>]

Eric Sandeen wrote:
> Eric Sandeen wrote:
>> 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>
> 
> Guys, this is SIMPLE, SAFE, and it fixes a CORRUPTION BUG.
> is it EVER going to get checked in?

Please take it in Tim, that nasty CORRUPTION word caught my attention :)

Cheers

> 
> -Eric
> 
>>>> 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
>>>
>>
> 
> 

-- 

  Mark Goodwin                                  markgw@sgi.com
  Engineering Manager for XFS and PCP    Phone: +61-3-99631937
  SGI Australian Software Group           Cell: +61-4-18969583
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