Early pl011 console for debugging KVM for ARM port

Early pl011 console for debugging KVM for ARM port

[Christoffer Dall]

Hi everyone.

I am working on a port of KVM for arm (http://android.chazy.dk) and I
am somewhat stuck. I encounter a crash somewhere in do_initcalls(),
but I do not have console at this point, as my only console is the
pl011 uart device. Not having the console makes it quite hard to track
down the bugs (an effort I do by placing asm("swi 0xMAGIC") at various
locations) for now.

Does anyone know how to enable such a console earlier? I tried simply
calling pl011_init() before the initcalls loop, but I eventually hit a
NULL pointer exception inside
list_add_tail(&kobj->entry,&kobj->kset->list); called from
kobject_add(...) in lib/kobject.c. I can gather it's the
kobj->kset->list.prev, which is NULL.

As far as I understand, these structures should have been initialized
at this point. Can anyone confirm?

Any help is greatly appreciated!


Thanks,
Christoffer Dall

Early pl011 console for debugging KVM for ARM port

[Baruch Siach]

Hi Christoffer,

On Wed, Dec 16, 2009 at 08:25:29PM -0500, Christoffer Dall wrote:
> Does anyone know how to enable such a console earlier?

The early_printk commit, which has recently been merged to the mainline, may 
help you. See commit 93fd03a8c6728b58879f8af20ffd55d9c32a778b and the link 
below.

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=93fd03a8c6728b58879f8af20ffd55d9c32a778b

baruch

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -

Early pl011 console for debugging KVM for ARM port

[Christoffer Dall]

Hi Baruch.

Got side tracked for a few days.

Thanks a lot. It works like a charm. I now know that the error happens
in different places on each execution, and I'm debugging that now.

Best,
Christoffer

On Wed, Dec 16, 2009 at 11:02 PM, Baruch Siach <baruch@tkos.co.il> wrote:
> Hi Christoffer,
>
> On Wed, Dec 16, 2009 at 08:25:29PM -0500, Christoffer Dall wrote:
>> Does anyone know how to enable such a console earlier?
>
> The early_printk commit, which has recently been merged to the mainline, may
> help you. See commit 93fd03a8c6728b58879f8af20ffd55d9c32a778b and the link
> below.
>
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=93fd03a8c6728b58879f8af20ffd55d9c32a778b
>
> baruch
>
> --
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ~. .~ ? Tk Open Systems
> =}------------------------------------------------ooO--U--Ooo------------{=
> ? - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -
>