Re: [Qemu-devel] [PATCH] Rewrite mmap_find_vma() to work fine on 64-bit hosts with 32-bit targets

[Kirill A. Shutemov]

On Mon, Dec 08, 2008 at 09:59:07PM +0100, Martin Mohring wrote:
> Kirill A. Shutemov wrote:
> > On Wed, Dec 03, 2008 at 02:50:57PM +0200, Kirill A. Shutemov wrote:
> >   
> >> On Wed, Dec 03, 2008 at 12:34:18PM +0000, Paul Brook wrote:
> >>     
> >>> On Wednesday 03 December 2008, Kirill A. Shutemov wrote:
> >>>       
> >>>> qemu's page table can be incomple if /proc/self/maps is unavailable or
> >>>> host allocating a memory with mmap(), so we can't use it to find free
> >>>> memory area.
> >>>>         
> >>> Do we really care? Do such systems exist?
> >>>       
> >> I use qemu-arm to build packages in restricted environment -- in hasher[1].
> >> hasher mounts /proc only for packages that really need it for building
> >> (java, for example).
> >>
> >> [1] http://en.altlinux.org/Hasher
> >>     
> >
> > Paul, do you have any objection or not? I really want to see it into
> > upstream.
> >
> >   
> One question I have though... What happens, if a start up script (ini
> script) run in qemu linux-user changes /proc/sys/vm/mmap_min_addr from 0
> to say 65536? Can this ever work, without later memory allocs with
> mmap() failing?

If I understood you correctly, it's one more reason for new
mmap_find_vma(). I guess, it should work fine, but I haven't tested this
case.

-- 
Regards,  Kirill A. Shutemov
 + Belarus, Minsk
 + ALT Linux Team, http://www.altlinux.org/

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