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Re: [Qemu-devel] [PATCH] possible mmap regression
From: |
Edgar E. Iglesias |
Subject: |
Re: [Qemu-devel] [PATCH] possible mmap regression |
Date: |
Wed, 20 Feb 2008 14:13:55 +0100 |
User-agent: |
Mutt/1.5.16 (2007-06-09) |
On Wed, Feb 20, 2008 at 03:03:39PM +0200, Felipe Contreras wrote:
> Hi Edgar,
>
> On Feb 16, 2008 11:07 PM, Edgar E. Iglesias <address@hidden> wrote:
> >
> > On Tue, Feb 12, 2008 at 09:42:15PM +0200, Felipe Contreras wrote:
> > > Hi,
> > >
> > > I don't know what I'm doing but this seems to fix the weird issue I was
> > > having.
> > > http://article.gmane.org/gmane.comp.emulators.qemu/23314
> > >
> > > I've found out that this happens on linux 2.6.23, but not 2.6.24.
> > >
> > > Cheers.
> > >
> > > --
> > > Felipe Contreras
> > > diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> > > index 6292826..3050ad9 100644
> > > --- a/linux-user/mmap.c
> > > +++ b/linux-user/mmap.c
> > > @@ -251,7 +251,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len,
> > > int prot,
> > > especially important if qemu_host_page_size >
> > > qemu_real_host_page_size */
> > > p = mmap(g2h(mmap_start),
> > > - host_len, prot, flags | MAP_FIXED, fd, host_offset);
> > > + host_len, prot, flags, fd, host_offset);
> > > if (p == MAP_FAILED)
> > > return -1;
> > > /* update start so that it points to the file position at
> > > 'offset' */
> >
> > Hello,
> >
> > Sorry, but I beleive your patch will break simulations where the targets
> > pagesize is larger than the hosts.
> >
> > Would you mind trying the attach patched and let us know if it helps for
> > you?
> > If not, it would be great if you could provide a small test case that trigs
> > the bug you are seeing so we can debug the problem.
> >
> > Best regards
> > --
> > Edgar E. Iglesias
> > Axis Communications AB
> >
> > diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> > index 6292826..78a8162 100644
> > --- a/linux-user/mmap.c
> > +++ b/linux-user/mmap.c
> > @@ -385,6 +385,9 @@ int target_munmap(abi_ulong start, abi_ulong len)
> > real_end -= qemu_host_page_size;
> > }
> >
> > + if (start < mmap_next_start)
> > + mmap_next_start = start;
> > +
> > /* unmap what we can */
> > if (real_start < real_end) {
> > ret = munmap(g2h(real_start), real_end - real_start);
> >
>
> I tried your patch and it still crashes.
>
> I sent the details before:
> http://article.gmane.org/gmane.comp.emulators.qemu/23314
> http://article.gmane.org/gmane.comp.emulators.qemu/23328
>
> Basically it was triggered by this change:
> http://repo.or.cz/w/qemu.git?a=commitdiff;h=edbcc0b2eb1d4caee5f293e5c79f81023f3394e2
>
> And it happens with some recursive Makefiles stuff.
Thanks Felipe,
I was also seeing errors with that commit. Later that same evening I found a
few more errors with the mmap code which tried to fix. Would you mind trying
that patch too?
You can find it here:
http://lists.gnu.org/archive/html/qemu-devel/2008-02/msg00331.html
Best regards
-
Edgar E. Iglesias
Axis Communications AB