From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dale Farnsworth" Date: Tue, 4 Mar 2003 17:07:08 -0700 To: Tom Rini , linuxppc-dev@lists.linuxppc.org Subject: Re: Patch boot/common/relocate.S to start kernel at 0x000c Message-ID: <20030305000708.GD4683@rover.farnsworth.org> References: <20030304191644.GA4524@rover.farnsworth.org> <3E64FD53.3030107@embeddededge.com> <20030304201302.GA4683@rover.farnsworth.org> <3E650AAF.7060804@embeddededge.com> <20030304230849.GB4683@rover.farnsworth.org> <3E6534FA.9070503@embeddededge.com> <20030304234253.GB17093@ip68-0-152-218.tc.ph.cox.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20030304234253.GB17093@ip68-0-152-218.tc.ph.cox.net> Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: On Tue, Mar 04, 2003 at 11:42:53PM +0000, Tom Rini wrote: > Thinking waaaay back, it was probably me doing something wrong. :) That was my first thought, since prep/head.S starts the kernel at 0xc. :) > The easy way to verify what really happens is to check out the MP code in > prep/misc.c. I would have thought that chrp smp would do the pmac thing > of calling back to the fw, but I could be wrong here.. prep/misc.c just starts the secondary cpu at 0xc0, __secondary_hold. It's ok for that to happen before cpu 0 runs the kernel, since prep/head.S runs it at 0xc. Pmacs also start the secondary at __secondary_hold, but after cpu 0 is already running the kernel, so it's not an issue. It looks to me like all ppc smp systems start their secondary cpus at __secondary_hold. (I'd like to know if I'm wrong about that.) Since __secondary_hold writes to 0x4 and only reads 0x0 looking for it's cpu id, I still like the "b __start" at 0x0. Thanks, -Dale ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/