[Bug 1349941] Re: qemu-ppc segfault on simple hello world

Tom Musta tommusta at gmail.com
Wed Jul 30 17:12:35 UTC 2014


This sounds like it could be the problem fixed by this:

    commit a70daba3771e96cc6b8fd3d11ed297ab13717018
    Author: Alexander Graf <agraf at suse.de>
    Date:   Thu Jun 5 11:39:43 2014 +0200

    linux-user: Tell guest about big host page sizes
    
    We tell the guest its page size via AUX vectors. The guest process then uses
    this page size as information on which boundaries it can mmap() things.
    
    However, if the host has a bigger page size granularity than the guest, it can
    not fulfill these mmap() requests - which falls apart when MAP_FIXED is passed
    to mmap.
    
    So in that case, let the guest know that we're running on a bigger page size
    granularity than the target would require.
    
    This fixes running qemu-ppc (TARGET_PAGE_SIZE=4k) on a 64k page size ppc64 host
    for me.
    
    Signed-off-by: Alexander Graf <agraf at suse.de>
    Reviewed-by: Richard Henderson <rth at twiddle.net>


or possibly by this:

    commit f46e9a0b9911fcfbc13f85f3a8808067990a0f5c
    Author: Tom Musta <tommusta at gmail.com>
    Date:   Thu May 29 09:12:23 2014 -0500

    target-ppc: Confirm That .bss Pages Are Valid
    
    The existing code does a check to ensure that a .bss region is properly
    mmap'd.  When additional mmap is required, the (guest) pages are also
    validated.  However, this code has a bug: when host page size is larger
    than target page size, it is possible for the .bss pages to already be
    (host) mapped but the guest .bss pages may not be valid.
    
    The check to mmap additional space is separated from the flagging of the
    target (guest) pages, thus ensuring that both aspects are done properly.
    
    Signed-off-by: Tom Musta <tommusta at gmail.com>
    Signed-off-by: Alexander Graf <agraf at suse.de>

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https://bugs.launchpad.net/bugs/1349941

Title:
  qemu-ppc segfault on simple hello world

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