From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 22 Jul 2004 16:55:36 -0700 From: Matt Porter To: Ralph Siemsen Cc: linuxppc-dev@lists.linuxppc.org Subject: Re: early UART mapping in head_44x.S Message-ID: <20040722165536.B20296@home.com> References: <40F452D6.9020806@rossvideo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <40F452D6.9020806@rossvideo.com>; from rsiemsen@rossvideo.com on Tue, Jul 13, 2004 at 05:23:34PM -0400 Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: On Tue, Jul 13, 2004 at 05:23:34PM -0400, Ralph Siemsen wrote: > > I've been trying to boot a vanilla 2.6.7 kernel on a board similar to > Ocotea (the board boots 2.4.x okay). I wasn't getting any serial > output, despite setting CONFIG_SERIAL_TEXT_DEBUG and doing early > registration of a console (as per David Woodhouse's posts on this list). That's a separate issue. I need to go through and early register the console on 4xx when I get a moment. > After much tracing and a lucky suggestion on IRC, I seem to have > stumbled on the cause, although I don't fully understand what is going > on. In arch/ppc/kernel/head_44x.S (from 2.6.7 mainline) there is a > block of code that sets up the "early UART mapping". It does three > tlbwe instructions, and then repeats the same a second time but in > "Translation state 1". This second set seems to cause my problems. > When I comment out the 5 instructions before the isync, I magically > start getting printk outputs. Yeah, I fat-fingered the last patch to head_44x.S and left the duplicate code fragment there. There's a patch submitted to fix this in mainline. -Matt ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/