musl - Re: [Qemu-devel] Re: Bogus struct stat64 for qemu-microblaze (user emulation)?

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Message-ID: <20140717233957.GB13728@toto>
Date: Fri, 18 Jul 2014 09:39:57 +1000
From: "Edgar E. Iglesias" <edgar.iglesias@...il.com>
To: Rich Felker <dalias@...c.org>
Cc: Peter Maydell <peter.maydell@...aro.org>,
	"Edgar E. Iglesias" <edgar.iglesias@...alogix.com>,
	musl@...ts.openwall.com, QEMU Developers <qemu-devel@...gnu.org>,
	microblaze-linux@...ts.itee.uq.edu.au,
	Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
Subject: Re: [Qemu-devel] Re: Bogus struct stat64 for qemu-microblaze
 (user emulation)?

On Wed, Jul 16, 2014 at 11:59:58AM -0400, Rich Felker wrote:
> On Wed, Jul 16, 2014 at 09:36:23AM +0100, Peter Maydell wrote:
> > On 16 July 2014 05:02, Rich Felker <dalias@...c.org> wrote:
> > > The qemu-microblaze definition of struct stat64 seems to mismatch the
> > > kernel definition, which is using asm-generic/stat.h. See:
> > >
> > > http://git.qemu.org/?p=qemu.git;a=blob;f=linux-user/syscall_defs.h;h=c9e6323905486452f518102bf40ba73143c9d601;hb=HEAD#l1469
> > > http://git.qemu.org/?p=qemu.git;a=blob;f=linux-user/syscall.c;h=a50229d0d72fc68966515fcf2bc308b833a3c032;hb=HEAD#l4949
> > >
> > > This seems to be causing a truncated-to-32-bit inode number to be
> > > stored in the location where st_ino should reside, and a spurious copy
> > > of the inode number to be written in a unused slot at the end of the
> > > structure.
> > 
> > Sounds quite plausible -- we've had issues with other archs
> > not having correct stat struct definitions in QEMU. I don't
> > suppose anybody's done much testing of the microblaze
> > linux-user code.
> 
> The bug seems to have been introduced here.
> 
> http://git.qemu.org/?p=qemu.git;a=commitdiff;h=a523eb06ec3fb2f4f4f4d362bb23704811d11379
> 
> I'm CC'ing the author/committer in case he has any input on why he did
> this.
> 
> > > Is my analysis correct? Stefan Kristiansson and I found this while
> > > working on the or1k port of musl libc, where it seems our structure
> > > for the existing microblaze port is wrongly aligned with the qemu
> > > definition rather than the definition the real kernel is using. Before
> > > I try correcting this on our side, I want to make sure we're working
> > > with the right version.
> > 
> > I would definitely trust the kernel definition, not QEMU's!
> 
> Yes.

Hi,

Yes, please trust the kernel.

We had a state of flux for a while where various ABIs circulated,
I don't remember the details.

If you create a patch and try both mb little and big-endian that
would be awesome.

Thanks,
Edgar


> 
> Rich
>

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