From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Mallick, Asit K" Date: Fri, 25 Jan 2002 22:57:09 +0000 Subject: RE: [Linux-ia64] Patch to fix latest kernels issue with FW83 Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org > -----Original Message----- > From: Bjorn Helgaas [mailto:bjorn_helgaas@hp.com] > Sent: Friday, January 25, 2002 8:08 AM > To: Mallick, Asit K; linux-ia64@linuxia64.org > Subject: Re: [Linux-ia64] Patch to fix latest kernels issue with FW83 > > > On Thursday 24 January 2002 12:46 pm, Mallick, Asit K wrote: > > We have root caused the stability problem with latest > kernels and FW83 > > (LION platform). The following patch (based on 2.4.17) fixes the > > problem. > ... > > - "ld4.bias r2 = [%0]\n" \ > > + "ld4 r2 = [%0]\n" \ > > Can you elaborate on this a bit? All I know about ld.bias is > the statement > in section 4.4.6.1 of Vol 1 that > > [ld.bias] is a hint to the implementation to acquire exclusive > ownership of the line containing the addressed data. The bias > hint does not affect program functionality and may be ignored > by the implementation. This is correcnt. > > I can believe the patch is a performance optimization (my > intuition is that > when the holder writes the lock to release it, the waiter will merely > invalidate its shared line, where it previously had to invalidate and > copyout its exclusive line), but I don't see how this should improve > stability. What am I missing? FW83 does not have a workaround for a chipset issue (chipset SAC errata#2 in 460GX specification update) that could cause a livelock with ld.bias loops and no modification. The later version of the FWs have the workaround and will not see this problem. Thanks, Asit