Date: Thu, 18 Feb 2010 10:53:06 +0100 From: Grzegorz Bernacki <gjb@semihalf.com> To: Rafal Jaworowski <raj@semihalf.com> Cc: rpaulo@gmail.com, freebsd-arm@FreeBSD.org, ticso@cicely7.cicely.de, ticso@cicely.de Subject: Re: kdump on ARM Message-ID: <4B7D0E02.6020708@semihalf.com> In-Reply-To: <A4F35738-2BE4-4E48-B6F7-6D14685305E2@semihalf.com> References: <20100217151607.GU43625@cicely7.cicely.de> <20100217151941.GV43625@cicely7.cicely.de> <20100217152900.GX43625@cicely7.cicely.de> <20100217.100004.321689434032786752.imp@bsdimp.com> <A4F35738-2BE4-4E48-B6F7-6D14685305E2@semihalf.com>
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Rafal Jaworowski wrote: > On 2010-02-17, at 18:00, M. Warner Losh wrote: > >> In message: <20100217152900.GX43625@cicely7.cicely.de> >> Bernd Walter <ticso@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
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