linux-kernel - Re: EFI Boot Stub Early Console

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Message-ID: <1332172989.4041.52.camel@mfleming-mobl1.ger.corp.intel.com>
Date:	Mon, 19 Mar 2012 16:03:09 +0000
From:	Matt Fleming <matt.fleming@...el.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Shea Levy <shea@...alevy.com>, "H. Peter Anvin" <hpa@...or.com>,
	linux-kernel@...r.kernel.org
Subject: Re: EFI Boot Stub Early Console

On Mon, 2012-03-19 at 15:56 +0000, Alan Cox wrote:
> > > 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...
> > 
> > Oops. Good point, that isn't going to work.
> 
> Surely it works fine if you are using bootstub directly from EFI ?

Yeah, up until the point you call ExitBootServices(), which is very
early in the boot process. After that you can't rely on the validity of
the console pointers in the system table.

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