[coreboot] New patch to review for coreboot: 1c4e003 Fixed broken MTRR for >4GB memory on AMD K8 fam 0fh rev <=E

Oskar Enoksson (enok@lysator.liu.se) gerrit at coreboot.org
Thu Oct 6 18:26:32 CEST 2011


Oskar Enoksson (enok at lysator.liu.se) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/238

-gerrit

commit 1c4e003269ed43e3d46c60f56e62bcb1049a3fc0
Author: Oskar Enoksson <enok at lysator.liu.se>
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 <enok at lysator.liu.se>
    Change-Id: Ie568a52a8eb355969c86964d5afc4692e60f69c1
---
 src/cpu/amd/mtrr/amd_mtrr.c |   18 +++++++++++++++---
 1 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/cpu/amd/mtrr/amd_mtrr.c b/src/cpu/amd/mtrr/amd_mtrr.c
index 623a344..93a3bba 100644
--- a/src/cpu/amd/mtrr/amd_mtrr.c
+++ b/src/cpu/amd/mtrr/amd_mtrr.c
@@ -112,7 +112,13 @@ 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 is_revF = 
+		((cpuid_eax(0x80000001)&0x00000f00)>>8 >= 0xf) ||
+		(((cpuid_eax(0x80000001)&0x00000f00)>>8 == 0xf) &&
+		 ((cpuid_eax(0x80000001)&0x000f0000)>>16 >= 0x4));
+	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 +174,9 @@ 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 +209,9 @@ 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);
 }




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