From mboxrd@z Thu Jan 1 00:00:00 1970 From: crn@pop3.netunix.com Date: Mon, 27 Dec 2010 17:28:19 +0000 Subject: Re: SPARC32 SMP IRQ15 question Message-Id: <7703a55121b37bcd7eb55aac851e7bfc.squirrel@webmail.gradwell.com> List-Id: References: <4D0A2102.8030100@gaisler.com> In-Reply-To: <4D0A2102.8030100@gaisler.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: sparclinux@vger.kernel.org > From: Kjetil Oftedal > Date: Sun, 26 Dec 2010 13:34:56 +0100 > >> On 22 December 2010 23:28, David Miller wrote: >>> From: Daniel Hellstrom >>> Date: Wed, 22 Dec 2010 14:23:27 +0100 >>> >>>> I will try to create a patch for the atomic layer for SMP LEON systems >>>> since they have the CASA instruction. >>> >>> But see my other posting, you still have to fix the irq15 problem. >>> >>> Merely switching to CASA doesn't mean you don't still have a problem >>> because spin_lock_irqsave() and other similar pieces of code expect >>> they will not be interrupted by smp_call_function() calls. >> >> Was SPARC32 SMP in 2.4 also implemented using IRQ15/NMI ? > > Yes, it's essentially always had this problem. > > It was less important back then because smp_call_function() was > really not used much by generic code. Now it's used everywhere. Maybe this could be why I could never get a sun4d SS1000E with 8 processors to stay up for more than a few minutes without locking solid. OTOH it could be irrelevant.