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Re: [Xen-devel] [PATCH] [Firmware] TCG BIOS extensions for the Bochs BIO

To: Stefan Berger <stefanb@xxxxxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] [Firmware] TCG BIOS extensions for the Bochs BIOS
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Fri, 08 Dec 2006 13:36:05 +0000
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On 8/12/06 13:30, "Stefan Berger" <stefanb@xxxxxxxxxx> wrote:

> Is there a good reason for it being implemented almost entirely in assembly
> language?


The compiled TCG extension code adds approximately 0x2500 bytes to the BIOS and would add more to it if it was written in 'C'.

Presumably only those who want TPM functionality will run with the TPM-enabled BIOS, and they are unlikely to care whether the implementation is e.g., 10kB or 15kB. Even people not using the TPM capabilities are not really going to care about a few kilobytes. It’s not like you’re constrained to 64kB (0xF0000-0xFFFFF) — you can stick the 32-bit code below 4GB.

 -- Keir
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