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Re: [Qemu-devel] qemu-user mmap not thread-safe?

From: Kirill A. Shutemov
Subject: Re: [Qemu-devel] qemu-user mmap not thread-safe?
Date: Wed, 20 Jun 2007 12:32:04 +0300
User-agent: Mutt/1.5.14 (2007-02-12)

On [Tue, 19.06.2007 16:03], Alexander Graf wrote:
> Paul Brook wrote:
> > On Thursday 24 May 2007, Alexander Graf wrote:
> >   
> >> Hi,
> >>
> >> while playing around with TLS on i386 i came across this problem which
> >> occurs even when no TLS is used at all. If two threads just malloc()
> >> memory all the time I get a segmentation fault after a short time. Might
> >> this be a serious bug?
> >>     
> >
> > qemu is not even vaguely threadsafe.
> >
> > Paul
> >
> >
> >   
> Hi,
> I somehow narrowed the problem down to x86_64. As soon as I use
> qemu-i386 on i386 or ppc the memory mapping tables are OK. When using
> x86_64 as host they are broken. Could this be a generic 64-bit host
> problem? I doubt that this actually has to do too much with the
> threading itself, because it works fine on other platforms.

On x86_64 mmap() sometimes return address above 4G. It is problem if target 
system is 32-bit. I use attached patch to solve it.

Regards,  Kirill A. Shutemov
 + Belarus, Minsk
 + Velesys LLC, http://www.velesys.com/
 + ALT Linux Team, http://www.altlinux.com/

Attachment: qemu-0.8.2-alt-mmap.patch
Description: Text document

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