[RFC] arm: Defer lookup of machine_type and vet of atags to setup.c

Russell King - ARM Linux linux at arm.linux.org.uk
Wed Jan 12 10:52:16 EST 2011

On Wed, Jan 12, 2011 at 08:46:44AM -0700, Grant Likely wrote:
> Looks like I've hit a hiccup though.  When I remove the first call to
> __lookup_machine_type, then it is only called after the MMU is turned
> on and the kernel is no longer able to output the list of configured
> machine ids when it doesn't recognize the value in r1 (tested with
> qemu versatile emulation).  I'm still investigating, so I'll defer
> reposting the patch until I've got this issue solved.

It only does this when DEBUG_LL is enabled - at which point you have
printascii, printhex8, etc available (although there's no prototype
for them.)

You could use snprintf() to format a message and then use printascii()
(conditional on CONFIG_DEBUG_LL as the existing code does) as well as
printk("%s", buffer).  That means if you have a debugger you can dump
the kernel ring buffer and see the message, or see it via the serial
port/debugging channel if DEBUG_LL is enabled.

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