Re: [Qemu-devel] [PATCH] migration: initialize RAM to zero

[Juan Quintela <quintela@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> wrote:
> Using qemu_memalign only leaves the RAM zero by chance, because libc
> will usually use mmap to satisfy our huge requests.  But memory will
> not be zero when using MALLOC_PERTURB_ with a nonzero value.  In the
> case of incoming migration, this breaks a recently-introduced
> invariant (commit f1c7279, migration: do not sent zero pages in
> bulk stage, 2013-03-26).
>
> To fix this, use mmap ourselves to get a well-aligned, always zero
> block for the RAM.  Mmap-ed memory is easy to "trim" at the sides.
>
> This also removes the need to do something special on valgrind
> (see commit c2a8238a, Support running QEMU on Valgrind, 2011-10-31).
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Except for the mmap return check and the missing valgrind check,  the
patch looks good.

Thanks,  Juan.