kdump on ARM

[Grzegorz Bernacki]

Rafal Jaworowski wrote:
> On 2010-02-17, at 18:00, M. Warner Losh wrote:
> 
>> In message: <20100217152900.GX43625 at cicely7.cicely.de>
>>            Bernd Walter <ticso at cicely7.cicely.de> writes:
>> : On Wed, Feb 17, 2010 at 04:19:41PM +0100, Bernd Walter wrote:
>> : > On Wed, Feb 17, 2010 at 04:16:07PM +0100, Bernd Walter wrote:
>> : > > On Wed, Feb 17, 2010 at 02:54:05PM +0000, Rui Paulo wrote:
>> : > > > On 17 Feb 2010, at 14:18, Grzegorz Bernacki wrote:
>> : > > > I wonder if this can't be made non arm conditional?
>> : > 
>> : > Ups - I'd just recovered from Mr. Sandman's work.
>> : > So we all agree about.
>> : > Nevertheless it should be verified if this is just a faulty struct
>> : > definition.
>> : > On the other hand I think it is not because someone else wrote it is
>> : > a brokem on mips as well.
>> : 
>> : I'm really still sleeping - noone mentioned mips at all.
>> : > > Either this struct is properly aligned or not.
>> : > > So why should this be made conditional?
>> : > > Non strict alignment architecturs also have problems with this, but
>> : > > it is usualy just speed penalties.
>> : > > There is one ARM sepcific struct missalignment problem.
>> : > > In this case we usually add __packed macro to structure definition.
>> : > > For most structures this usually means no change on other
>> : > > archtitectures and we only declare the struct to forcibly be what the
>> : > > programmer already expected.
>> : > > Only a few programmers are aware that they expect something from
>> : > > structures, which is not garantied.
>>
>> This code is clearly nutso when it comes to alignment.  I've come up
>> with a slightly better patch.  I'd though about doing the structure
>> assignment that I suggested in a prior note, but the compiler is free
>> to assume alignment when copying the structures, which may end badly.
>> There's no way we can add __packed or __aligned easily to this code
>> (although the ktrstat and ktrsockaddr routines should be able to have
>> that annotation, a quick test suggests that the annotations I tried
>> didn't take right).
>>
>> I don't have a good ARM setup at the moment to actually test these
>> changes.  Can others test them?  They seem to work for me on x86, but
>> that isn't saying much.
> 
> Thanks, this looks better. We'll test this in our set-up and verify, but only tomorrow I guess...
> 
> Rafal
> 

Yes, this patch is much better. I've tested it on ARM and it works fine.

grzesiek