Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible

From: Ingo Molnar
Date: Tue Apr 07 2015 - 06:24:56 EST

* Alexander Kuleshov <kuleshovmail@xxxxxxxxx> wrote:

> 2015-04-07 15:52 GMT+06:00 Ingo Molnar <mingo@xxxxxxxxxx>:
> >
> > It would be nice to test it via a well placed printk() and check that
> > before the patch the message doesn't go to the serial console and
> > after the patch the message indeed arrives on the early serial console
> > - or something like that.
> I have tested this patch when i wrote it and early_printk does not print
> anything before the parse_early_param. But i don't know how to show this
> in code in a correct way. [...]

Just add a debug printk() for your own testing, right after the param
initialization call, to be confident that the early console indeed

> which i removed in the previous patch
> (
> Any one another question about this. I submited patch only for
> head64.c and it does not affect kernel for i386, because i'm not
> sure where is the best place to setup earlyprintk in the head32.c. I
> thought to put it in the start of i386_start_kernel(void) (from
> head32.c) but not sure about it.

I'd use i386_start_kernel() on 32-bit and x86_64_start_kernel() on
64-bit - but I haven't tested whether it actually works.


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