From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from xm.dlasys.net (unknown [24.152.213.223]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id A68E068775 for ; Sat, 19 Nov 2005 10:19:47 +1100 (EST) Received: from [206.223.20.141] (port=1211 helo=[206.223.20.141]) by xm.dlasys.net with esmtp (Exim 4.54 #1 (Debian)) id 1EdbZS-0001xP-0N for ; Sat, 19 Nov 2005 17:52:34 -0500 Message-ID: <437E606D.20601@dlasys.net> Date: Fri, 18 Nov 2005 18:14:53 -0500 From: "David H. Lynch Jr." MIME-Version: 1.0 To: linuxppc-embedded References: <20051118024803.E2988687A1@ozlabs.org> In-Reply-To: <20051118024803.E2988687A1@ozlabs.org> Content-Type: text/plain; charset=GB2312 Subject: Re: Help ! 2.6.14 kernel can't bring up Reply-To: dhlii@comcast.net List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , zjznliang wrote: > Hi linuxppc-embeddedŁĄ > > Hi , How to config the "early printk" in 2.6.14 linux configration??? > > > Console and debugging I/O is available at all stages of The Linux loading process - If the drivers for your board support it. There is nearly free support for 8250 like serial ports, in virtually all boards. Support for other debugging IO devices is fairly simple to setup. I used the arch/ppc/syslib/mv64x60_dbg.c and arch/ppc/boot/simple/mv64x60_tty.c as templates to create trivial drivers for debugging IO on hardware that had no relation to a UART. I think "early printk" refers to the early serial driver that can be used after the kernel has uncompressed itself and relocated itself and switched to a virtual environment. For 8250 like serial ports that can enabled in the linux .config file setup by make menuconfig or whatever variant of make xxconfig you prefer. For non-8250 like uarts you will again have to write an early serial driver. All the early debug IO drivers are trivial - little more is needed than an implementation of putc, as opposed to the full conolse support required for a tty on a booted system.