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

From: "Edgar E. Iglesias" <edgar.iglesias-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Rich Felker <dalias-8zAoT0mYgF4@public.gmane.org>
Cc: Peter Maydell
	<peter.maydell-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	microblaze-linux-FR6EJeJVuqfA6Z3fQjNZrN9u6TNh0Fb7@public.gmane.org,
	musl-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org,
	QEMU Developers
	<qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org>,
	Stefan Kristiansson
	<stefan.kristiansson-MbMCFXIvDHJFcC0YU169RA@public.gmane.org>,
	"Edgar E. Iglesias"
	<edgar.iglesias-g5w7nrANp4BDPfheJLI6IQ@public.gmane.org>
Subject: Re: [Qemu-devel] [musl] Re: Bogus struct stat64 for qemu-microblaze (user emulation)?
Date: Fri, 18 Jul 2014 09:39:57 +1000	[thread overview]
Message-ID: <20140717233957.GB13728@toto> (raw)
In-Reply-To: <20140716155957.GL17402-C3MtFaGISjmo6RMmaWD+6Sb1p8zYI1N1@public.gmane.org>

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-8zAoT0mYgF4@public.gmane.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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