[coreboot] [RFC] SMM handling and resident coreboot

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Tue Jul 29 00:44:11 CEST 2008

On 28.07.2008 21:22, Marc Jones wrote:
> Stefan Reinauer wrote:
>> Another alternative to keeping full coreboot around, would be to make
>> the SMM handler self contained. This would mean, the SMM handler could
>> not use coreboot's functions like printk_debug, pci_read_config32, it
>> could not use the device tree, and it would become more complex, because
>> for some information we have to reprobe the hardware, or parse the
>> coreboot table.
> I think you need to consider keeping the runtime smm code
> self-contained. Executing code from SMM that is outside the SMM
> protected memory region could be risky. printk is a convenient way to
> debug SMM but it shouldn't be used runtime in a normal system since
> Linux could be using the serial port. 

That's why we have the ability to tell printk to log to a memory buffer

> PCI read/write functions are not so duplication shouldn't be too bad.

PCI config read/write is probably the one thing we never want to do in
SMM because the OS could be in the middle of an CF8/CFC cycle.



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