From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 6951EDDF70 for ; Fri, 13 Feb 2009 13:46:46 +1100 (EST) Subject: Re: [PATCH] powerpc: Add support for using doorbells for SMP IPI From: Benjamin Herrenschmidt To: Kumar Gala In-Reply-To: <1234482893-17712-1-git-send-email-galak@kernel.crashing.org> References: <1234482893-17712-1-git-send-email-galak@kernel.crashing.org> Content-Type: text/plain Date: Fri, 13 Feb 2009 13:46:40 +1100 Message-Id: <1234493200.29851.79.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2009-02-12 at 17:54 -0600, Kumar Gala wrote: > The e500mc supports the new msgsnd/doorbell mechanisms that were added in > the Power ISA 2.05 architecture. We use the normal level doorbell for > doing SMP IPIs at this point. > Cool stuff. Haven't reviewed in details yet tho :-) But I was thinking... We should introduce a special xmon variant of local_irq_save/restore for use by xmon that masks MSR:CE and use a crit doorbell for xmon IPI, that would increase significantly the ability of xmon to catch deadlocked CPUs, and we could use external CRITs as a more generic way of doing IPIs, no ? In fact, we should expose a local_crit_irq_save/restore (disable/enable) too for things like watchdog drivers etc... which may want to use these. Cheers, Ben.