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From: Mayank J. <con...@gm...> - 2008-12-19 04:56:54
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Hi, is there anything i can help with can u plz let me know what exactly is the problem and can u plz give me access to the source code On 12/17/08, Julian Seward <js...@ac...> wrote: > On Wednesday 17 December 2008, Bart Van Assche wrote: >> On Wed, Dec 17, 2008 at 4:05 AM, Peter Wemm <pe...@we...> wrote: >> > [...] It does not work reliably with pthreads though due to an >> > architectural issue (libvex doesn't do atomic operations, which >> > doesn't mix well with the umtx syscalls that FreeBSD's threads uses.) [ >> > ...] >> >> Both the Helgrind and DRD tools have some support for atomic >> operations. I don't know from the top of my head when exactly support >> for atomic operations was added to VEX. > > This is a different problem, that Peter explained on this list a couple > of weeks back. The problem is that VEX breaks up LOCK-prefixed > read-modify-write instructions so that they are no longer atomic. This > causes Valgrinded processes using such instructions to lose races against > other processes (or the FreeBSD kernel) when the other processes also > use LOCK-prefixed instructions on those same locations. > > Fixing this will require some considerable hacking around inside both > VEX and various of the Valgrind tools. I plan to have a look at it > over the Christmas break. > > J > |