linux-kernel - Re: EFI Boot Stub Early Console

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4F65D09B.4050807@shealevy.com>
Date:	Sun, 18 Mar 2012 08:10:03 -0400
From:	Shea Levy <shea@...alevy.com>
To:	Matt Fleming <matt.fleming@...el.com>
CC:	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: EFI Boot Stub Early Console

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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/