Re: Booting and debugging Linux on IXDP425
From: Charles Oram (charlesoram_at_hotmail.com)
Date: 07/31/03
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Date: 30 Jul 2003 21:32:22 -0700
Charles Oram wrote in message news:<498c79aa.0307291610.2934eb36@posting.google.com>...
> Hi there,
> I am trying to get Linux to boot on an IXDP425 board (Intel IXP425
> development board) with no luck. I have Redboot running OK, but when I
> load zImage and ask Redboot to run it with "exec" it locks up and
> nothing happens (no "uncompressing..." prompt or anything). I'm using
> the Snapgear Linux distribution. I have tried a precompiled Linux
> image from the Gatewaymaker project
> (http://gatewaymaker.sourceforge.net/) and get the same result.
> What I'd like to do is step through the Linux startup code with my
> debugger, but I have a few questions about doing this.
>
> I'm using a home made "Wiggler" parallel port JTAG adapter. This seems
> to work fine (although I have to run OcdLibRemote on a Windows PC)
> with GDB for small simple programs (I used it to load my program that
> programmed Redboot into the Flash), but I cannot connect to the target
> and make it run Redboot (either out of ROM or RAM). Surely I should be
> able to connect to the target with GDB and the Wiggler and just tell
> it to continue and have it run Redboot?
> If I try to run Redboot from Flash with GDB and the Wiggler I get a
> "Target Bus Error" from OcdLibRemote as soon as I single step on the
> first instruction at 0x0.
>
> The other thing that confuses me is how to make sure that my Linux
> image is located correctly. The latest version of Redboot for the
> IXDP425 seems to want to run Linux from 0x6000000. As far as I can
> make out I should be able to edit vmlinux.lds to make sure that it is
> built to load there, but that doesn't make any difference and there
> are several vmlinux.lds files (which one is used, arch/arm/vmlinux.lds
> or arch/arm/boot/compressed/vmlinux.lds ?).
>
> Any advice would be greatly appreciated.
>
> - Charles
It turns out that a few things (ignorance and misfortune!) were
plotting against me.
Firstly, the Linux kernel uses UART0 as the default console, and I
have been running Redboot on UART1.
Secondly, my UART0 RS232 driver chip is stuffed on my IXDP425! So even
though I had tried using UART0 I still didn't see anything (and hadn't
realised that Redboot can automatically use either).
Recompiling the kernel to use UART1 has at last produced the famous
"Uncompressing Linux..." message.
As to some of my other questions - well, it turns out that Redboot
does enable the MMU on the IXP425, so that may well be why I have
limited success in trying to run Redboot using GDB and the Wiggler (I
have seen mention somewhere that cheap solutions like the Wiggler
don't work well with the MMU).
- Charles
- Previous message: Mirek: "bcl patch ?"
- In reply to: Charles Oram: "Booting and debugging Linux on IXDP425"
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