linux-kernel - Re: [PATCH 3/4] driver: provide sysfs interfaces to access TXT log

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Date:	Thu, 9 May 2013 12:02:18 +0000
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	"Ren, Qiaowei" <qiaowei.ren@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"platform-driver-x86@...r.kernel.org" 
	<platform-driver-x86@...r.kernel.org>,
	"Wei, Gang" <gang.wei@...el.com>
Subject: Re: [PATCH 3/4] driver: provide sysfs interfaces to access TXT log

On Thu, 2013-05-09 at 08:05 +0000, Ren, Qiaowei wrote:
> On 2013-05-08, Matthew Garrett wrote:
> > How different are these logs to the TPM measurements exported via
> > securityfs?
> 
> These logs come from tboot (Trusted Boot, an open source, pre-kernel/VMM module that uses Intel® Trusted Execution Technology (Intel® TXT) to perform a measured and verified launch of an OS kernel/VMM.), and should be different from those TPM measurements (from BIOS?) exported via security.

Different in what way? What are they actually logging?

> > So I write a value here and then I see different chunks of log? This
> > doesn't seem like an optimal interface. What do these logs actually
> > contain? How do I know which block I should be reading?
> 
> Yes. Since total log size is bigger than one page 4K, the log have to be displayed in 4K-block indexed by block_index.
> These logs will be very helpful for txt related debugging.

If they're only intended for debugging then sysfs probably isn't the
best place for them. debugfs might make more sense.

-- 
Matthew Garrett | mjg59@...f.ucam.org