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Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation
From: |
Matthew Wilcox |
Subject: |
Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation |
Date: |
Fri, 28 Dec 2018 17:54:54 -0800 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
On Sat, Dec 29, 2018 at 12:12:27AM +0000, Peter Maydell wrote:
> On Fri, 28 Dec 2018 at 23:16, Andreas Dilger <address@hidden> wrot
> > On Dec 28, 2018, at 4:18 AM, Peter Maydell <address@hidden> wrote:
> > > The problem is that there is no 32-bit API in some cases
> > > (unless I have misunderstood the kernel code) -- not all
> > > host architectures implement compat syscalls or allow them
> > > to be called from 64-bit processes or implement all the older
> > > syscall variants that had smaller offets. If there was a guaranteed
> > > "this syscall always exists and always gives me 32-bit offsets"
> > > we could use it.
> >
> > The "32bitapi" mount option would use 32-bit hash for seekdir
> > and telldir, regardless of what kernel API was used. That would
> > just set the FMODE_32BITHASH flag in the file->f_mode for all files.
>
> A mount option wouldn't be much use to QEMU -- we can't tell
> our users how to mount their filesystems, which they're
> often doing lots of other things with besides running QEMU.
> (Otherwise we could just tell them "don't use ext4", which
> would also solve the problem :-)) We need something we can
> use at the individual-syscall level.
Could you use a prctl to set whether you were running in 32 or 64 bit
mode? Or do you change which kind of task you're emulating too often
to make this a good idea?
- [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Florian Weimer, 2018/12/27
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Andy Lutomirski, 2018/12/27
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Peter Maydell, 2018/12/27
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Andreas Dilger, 2018/12/28
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Peter Maydell, 2018/12/28
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Andreas Dilger, 2018/12/28
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Peter Maydell, 2018/12/28
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation,
Matthew Wilcox <=
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Andy Lutomirski, 2018/12/29
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Peter Maydell, 2018/12/30
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Theodore Y. Ts'o, 2018/12/28
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Dominique Martinet, 2018/12/28
- Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Theodore Y. Ts'o, 2018/12/28
- Re: [Qemu-devel] [V9fs-developer] d_off field in struct dirent and 32-on-64 emulation, Dominique Martinet, 2018/12/28
Re: [Qemu-devel] d_off field in struct dirent and 32-on-64 emulation, Adhemerval Zanella, 2018/12/27