From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: In-Reply-To: <1175041735.14065.37.camel@localhost.localdomain> References: <20070327222840.GA1266@mag.az.mvista.com> <17929.44043.728362.712648@cargo.ozlabs.ibm.com> <20070328001215.GA25080@mag.az.mvista.com> <1175041735.14065.37.camel@localhost.localdomain> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: From: Segher Boessenkool Subject: Re: [PATCH] powerpc: Disable external interrupts in bootwrapper Date: Wed, 28 Mar 2007 18:52:33 +0200 To: Benjamin Herrenschmidt Cc: linuxppc-dev , Paul Mackerras List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >>>> Disable external interrupts very early in the bootwrapper in case >>>> the firmware left a device generating interrupts. >>> >>> Sounds reasonable, except that I wonder if systems running under a >>> real OF want to do this... >> >> I don't know. Would someone who knows OF speak up? > > OF isn't supposed to use external interrupts That isn't a hard rule. But yeah, hardly any OF will ever use interrupts for normal operation -- the kernel can have taken control of the exception vector and still want to access devices via OF, for example. > but I wouldn't bet on what > Apple's one does... I think it's not safe to do that thus on OF based > platforms. Until you take control of the external interrupt and decrementer interrupt (and overtemp interrupt, on some CPUs), you really shouldn't turn off the EE bit for extended periods of time. Set EE=0 right before the earliest of a) you want OF to be dead dead dead; or b) you copy the kernel's exception vectors to 0; and all will be fine. Segher