Patch set updated for coreboot: 4780961 Fixed broken MTRR for >4GB memory on AMD K8 fam 0fh rev <=E

[Oskar Enoksson]

Oskar Enoksson ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/238

-gerrit

commit 478096179cbc7c777641dda7ac1a7f1cce7d400e
Author: Oskar Enoksson 
Date:   Thu Oct 6 18:21:19 2011 +0200

Fixed broken MTRR for >4GB memory on AMD K8 fam 0fh rev <=E

AMD K8 rev F and later implements a bit SYSCFG_MSR_TOM2WB in SYSCFG_MSR to
    mark dram memory above 4GB as WB. However, AMD K8
    rev E and earlier don't implement this bit and therefore need
    MTRR spanning dram memory above 4GB. The current implementation
    of amd_setup_mtrrs never generate MTRR above 4GB.
    This caused memory > 4GB not to be recognized in e.g. Linux on those
    rev E or older platforms. This commit should fix that bug.

Signed-off-by: Oskar Enoksson 
    Change-Id: Ie568a52a8eb355969c86964d5afc4692e60f69c1
---
 src/cpu/amd/mtrr/amd_mtrr.c |   19 ++++++++++++++++---
 1 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/cpu/amd/mtrr/amd_mtrr.c b/src/cpu/amd/mtrr/amd_mtrr.c
index 623a344..7d15b84 100644
--- a/src/cpu/amd/mtrr/amd_mtrr.c
+++ b/src/cpu/amd/mtrr/amd_mtrr.c
@@ -112,7 +112,14 @@ void amd_setup_mtrrs(void)
    struct mem_state state;
    unsigned long i;
    msr_t msr, sys_cfg;
-
+	// Test if this CPU is a Fam 0Fh rev. F or later
+	const int cpu_id = cpuid_eax(0x80000001);
+	const int is_revF = 
+		 (((cpu_id>>8 )&0xf) >= 0xf) || // Family > 0F
+		((((cpu_id>>8 )&0xf) == 0xf) && // Family == 0F
+		 (((cpu_id>>16)&0xf) >= 0x4));  // Rev>=F deduced from rev tables
+	if(is_revF)
+		printk(BIOS_DEBUG, "Detected CPU Fam 0Fh rev.F or later\n");

/* Enable the access to AMD RdDram and WrDram extension bits */
    disable_cache();
@@ -168,7 +175,9 @@ void amd_setup_mtrrs(void)
    	msr.hi = state.tomk >> 22;
    	msr.lo = state.tomk << 10;
    	wrmsr(TOP_MEM2, msr);
-		sys_cfg.lo |= SYSCFG_MSR_TOM2En | SYSCFG_MSR_TOM2WB;
+		sys_cfg.lo |= SYSCFG_MSR_TOM2En;
+		if(is_revF)
+			sys_cfg.lo |= SYSCFG_MSR_TOM2WB;
    }

/* zero the IORR's before we enable to prevent
@@ -201,5 +210,9 @@ void amd_setup_mtrrs(void)
    /* Now that I have mapped what is memory and what is not
     * Setup the mtrrs so we can cache the memory.
     */
-	x86_setup_var_mtrrs(address_bits, 0);
+
+	// Rev. F K8 supports has SYSCFG_MSR_TOM2WB and dont need
+	// variable MTRR to span memory above 4GB
+	// Lower revisions K8 need variable MTRR over 4GB
+	x86_setup_var_mtrrs(address_bits, is_revF ? 0 : 1);
 }