From: Kurt Garloff <garloff@xxxxxxx>
Subject: The microcode may be smaller than the default size.
Patch-mainline: Never (but patch to non-xen microcode in 2.6.19rc)

This is the needed piece to the dom0 xen kernel to allow microcode
updates of non default size (2000+48 bytes); a patch is needed
to the Xen hypervisor itself as well.

Signed-off-by: Kurt Garloff <kurt@xxxxxxxxxx>

This corresponds to a patch to the microcode driver in 2.6.19rc
from Sep 27 2006:
> # User Shaohua Li <shaohua.li@xxxxxxxxx>
> # Node ID 45898b908138b5d93c2cc7353f061ce54af145dc
> # Parent  f962eab7b82c9bf1a6da69571046e764f5128395
> [PATCH] x86 microcode: don't check the size
> 
> IA32 manual says if micorcode update's size is 0, then the size is
> default size (2048 bytes). But this doesn't suggest all microcode
> update's size should be above 2048 bytes to me. We actually had a
> microcode update whose size is 1024 bytes. The patch just removed the
> check.
> 
> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
> Cc: Tigran Aivazian <tigran@xxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxx>
> 
> committer: Linus Torvalds <torvalds@xxxxxxxxxxx> 1159370778 -0700

--- linux-2.6.16-SLES10_GA_BRANCH/arch/i386/kernel/microcode-xen.c.orig	2006-09-25 22:04:41.000000000 +0200
+++ linux-2.6.16-SLES10_GA_BRANCH/arch/i386/kernel/microcode-xen.c	2006-12-24 17:08:37.000000000 +0100
@@ -85,7 +85,7 @@
 {
 	ssize_t ret;
 
-	if (len < DEFAULT_UCODE_TOTALSIZE) {
+	if (len < MC_HEADER_SIZE) {
 		printk(KERN_ERR "microcode: not enough data\n"); 
 		return -EINVAL;
 	}