From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from web38901.mail.mud.yahoo.com (web38901.mail.mud.yahoo.com [209.191.125.107]) by ozlabs.org (Postfix) with SMTP id A06EDDDDA2 for ; Fri, 3 Apr 2009 07:12:39 +1100 (EST) Message-ID: <52907.72158.qm@web38901.mail.mud.yahoo.com> Date: Thu, 2 Apr 2009 13:05:58 -0700 (PDT) From: Yigal Goldberger Subject: early kernel debugging To: linuxppc-dev@ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi All, I'm using u-boot to boot kernel 2.6.24.2 on a powerpc based board . I see that after uncompressing the kernel it hangs. I found a location (System.map) I think corresponds to the __log_buf (my SDRAM starts at physical address 0 (and u-boot performs -> Load Address: 00000000 Entry Point: 00000000) . So I just removed the leading C0xxxxxx from the address leaving xxxxxx . And that's where I looked . I did see 2 error messages (though they were somewhat corrupt) the first designated a memory fault and the second a kernel oops at some address. I looked this address up on System.map and it's somewhere inside prom.c in of_scan_flat_dt( ) . I have a few question at this point : A)Am I looking at the right memory location for __log_buf ? B)What is printed to the buffer (printk's of what verbose level ?) C)In a previous kernel version 2.6.14 I don't remember explicitly using a flat device tree or pointing at such a tree through the bootm command) , but I used the ARCH=ppc then as opposed to ARCH=powerpc Now . I see a lot of stuff regarding the need to provide such a data structure upon booting via bootm .Do I need to explicitly prepare such a data structure and provide a pointer to it via bootm ? Might this be the cause for this early hang ? Best Regards, Yigal Goldberger.