[coreboot] [PATCH] disabling microcode update

Scott Duplichan scott at notabs.org
Mon Feb 21 15:44:35 CET 2011


-----Original Message-----
From: coreboot-bounces+scott=notabs.org at coreboot.org [mailto:coreboot-bounces+scott=notabs.org at coreboot.org] On Behalf Of Xavi
Drudis Ferran
Sent: Monday, February 21, 2011 07:48 AM
To: Stefan Reinauer; coreboot at coreboot.org
Subject: Re: [coreboot] [PATCH] disabling microcode update


]Rationale for disabling microcode update:
]
]Ivaylo and I have had issues when updating microcode in FAM10
]
]We dont' have source for it (if it exists at all)

This really isn't relevant, but microcode patch source code
certainly exists, as does source code for the main microcode
that the patch modifies. A microcode assembler converts the
source code into binary form.

Think about what it would take for public microcode patch source
code to be useful. First, the processor vendor would have to 
publish the thousands of lines of source code for the microcode
that will be patched. Next, the microcode assembler and related
tools would have to be published. At that point, a lot of training
is needed to even understand the microcode. Microcode is not
written in any standard programming language. The language is 
completely different for different processor vendors, and even for
different processor models in some cases. Anyway, assume that
somehow a non-employee became a microcode expert for a particular
processor model. Why would the patch need to be modified? The
patch corrects a processor erratum. To modify microcode in a way
that works around a processor erratum usually requires details of
the processor design that are not published.

When a processor is purchased, its source code is not provided. The
microcode patch is a modification of the processor design, so it is
not surprising the source code is not supplied.

Thanks,
Scott





 Next, the processor vendor will have to
publish the source code to the microprocessor itself. The 
microprocessor source code is needed 






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