Re: EFI Boot Stub Early Console

[Shea Levy]

Hi Matt,

On 3/18/12 7:21 AM, Matt Fleming wrote:
> I don't think you'll need to use the graphics protocols, you should 
> just be able to put something together using the 'output_string' 
> function from the EFI simple text output protocol, e.g. something like 
> this, https://lkml.org/lkml/2012/3/16/193 

From the UEFI 2.3.1 spec:

> Prior to a call to ExitBootServices(), all of the fields of the EFI 
> System Table are valid. After an operating system has taken control of 
> the platform with a call to ExitBootServices(), only the Hdr, 
> FirmwareVendor, FirmwareRevision, RuntimeServices, 
> NumberOfTableEntries, and ConfigurationTable fields are valid.

Doesn't this mean that ConOut can't be used for the earlyprintk, since 
any bootloader (including the bootstub) will call ExitBootServices() 
before any printk'ing actually happens?? Or am I misunderstanding the 
spec somehow? I suppose I could just try it and see what happens...

Cheers,
Shea

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