[coreboot] Where does printk(DEBUG, "msg") go after booting?

Stefan Reinauer stefan.reinauer at coresystems.de
Tue Nov 30 19:18:27 CET 2010

There is/used to be some code that sets the baud rate to coreboots default on every SMM entry if SMM debug is enabled. Might mess up whatever the OS is doing though, it's not recovering the OS specified values.

On 30.11.2010, at 09:35, "Scott Duplichan" <scott at notabs.org> wrote:

> From: coreboot-bounces at coreboot.org [mailto:coreboot-bounces at coreboot.org] On Behalf Of Patrick Georgi
> Sent: Tuesday, November 30, 2010 11:26 AM
> To: coreboot at coreboot.org
> Subject: Re: [coreboot] Where does printk(DEBUG, "msg") go after booting?
> Hash: SHA1
> Am 30.11.2010 18:16, schrieb Fengwei Zhang:
>> I understand the printk(DEBUG, "msg") statement will print out msg on
>> the serial port when booting. How about after booting? Where does
>> printk(DEBUG, "msg") go after booting?
> ]"After booting" the only component that might still be active (and thus
> ]able to run our printk) would be SMM. That code shares the same printing
> ]routines, so it prints on serial, too.
> One thing to watch for is the OS changing the baud rate. I notice this with
> coreboot+seabios and DOS after CtrlAltDel. DOS sets the baud rate to 2400.
> The serial output is still present, but the baud rate must be changed to see it.
> Thanks,
> Scott
> Patrick
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