From: Geoff Gustafson <grgustaf@redhat.com>
Subject: [RHEL5 PATCH] remove microcode size check (bz 209455, 214798)
Date: Thu, 09 Nov 2006 10:55:43 -0500
Bugzilla: 214798
Message-Id: <45534F7F.5070902@redhat.com>
Changelog: remove microcode size check for i386


This patch was posted to IT by Intel to remove a size check that 
prevents the latest microcode update package (v1.15) from being loaded. 
It was overlooked, and probably there should be a separate bz for the 
kernel work vs. microcode_ctl, so I just opened 214798.

The patch is upstream here:
http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=bd8e39f9e4c0960541c8c69e1f7cb321574d7c90 


I have tested with kernel-2.6.18-1.2745.el5 on a Core 2 Duo desktop. 
Without the patch, doing "service microcode_ctl start" with microcode 
package 1.13 works, but 1.15 doesn't. With the patch, both work.

Microcode 1.15 contains updates for Intel's latest CPUs.

- Geoff



Index: linux-2.6.17.x86_64/arch/i386/kernel/microcode.c
===================================================================
--- linux-2.6.17.x86_64.orig/arch/i386/kernel/microcode.c	2006-09-13 13:12:33.000000000 +0800
+++ linux-2.6.17.x86_64/arch/i386/kernel/microcode.c	2006-09-13 13:22:19.000000000 +0800
@@ -250,14 +250,14 @@ static int find_matching_ucodes (void) 
 		}
 
 		total_size = get_totalsize(&mc_header);
-		if ((cursor + total_size > user_buffer_size) || (total_size < DEFAULT_UCODE_TOTALSIZE)) {
+		if (cursor + total_size > user_buffer_size) {
 			printk(KERN_ERR "microcode: error! Bad data in microcode data file\n");
 			error = -EINVAL;
 			goto out;
 		}
 
 		data_size = get_datasize(&mc_header);
-		if ((data_size + MC_HEADER_SIZE > total_size) || (data_size < DEFAULT_UCODE_DATASIZE)) {
+		if (data_size + MC_HEADER_SIZE > total_size) {
 			printk(KERN_ERR "microcode: error! Bad data in microcode data file\n");
 			error = -EINVAL;
 			goto out;
@@ -460,11 +460,6 @@ static ssize_t microcode_write (struct f
 {
 	ssize_t ret;
 
-	if (len < DEFAULT_UCODE_TOTALSIZE) {
-		printk(KERN_ERR "microcode: not enough data\n"); 
-		return -EINVAL;
-	}
-
 	if ((len >> PAGE_SHIFT) > num_physpages) {
 		printk(KERN_ERR "microcode: too much data (max %ld pages)\n", num_physpages);
 		return -EINVAL;