svn commit: r198868 - in head/sys: amd64/amd64 i386/i386

Attilio Rao attilio at freebsd.org
Wed Nov 4 16:06:38 UTC 2009


2009/11/4, Kostik Belousov <kostikbel at gmail.com>:
> On Wed, Nov 04, 2009 at 01:49:41PM +0100, Attilio Rao wrote:
> > 2009/11/4 Ed Schouten <ed at 80386.nl>:
> > > Hi Attilio,
> > >
> > > * Attilio Rao <attilio at FreeBSD.org> wrote:
> > >> Opteron rev E family of processor expose a bug where, in very rare
> > >> ocassions, memory barriers semantic is not honoured by the hardware
> > >> itself. As a result, some random breakage can happen in uninvestigable
> > >> ways (for further explanation see at the content of the commit itself).
> > >
> > > Ooh. Sounds like an interesting bug.
> > >
> > > The bug doesn't manifest itself on UP, right? If so, maybe we should add
> > > some very short instructions to the warning on how to disable SMP.
> >
> > Due to the semantic of the bug, I think that it can manifest itself on
> > UP and a memory barrier failing on UP means that PREEMPTION can blow
> > up. Considering this I wouldn't suggest anything different between the
> > UP vs SMP case.
>
> CPU is always self-consistent, isn't it ?
>
> Also, I very much dislike idea of making our kernel a collection of
> references to the man pages and URLs, esp. when URL point to the
> resource not controlled by the project.

Ok, as long as you are in favor of stripping the URL, I'm fine with it.

Attilio


-- 
Peace can only be achieved by understanding - A. Einstein


More information about the svn-src-head mailing list