linux-kernel - Blacklist DMAR on Intel G31/G33 chipsets

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Date:	Wed, 03 Sep 2008 11:53:51 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	linux-kernel@...r.kernel.org
Cc:	andi@...stfloor.org, arjan@...radead.org
Subject: Blacklist DMAR on Intel G31/G33 chipsets

Some BIOSes (the Intel DG33BU, for example) wrongly claim to have DMAR
when they don't. Avoid the resulting crashes when it doesn't work as
expected.

Signed-off-by: David Woodhouse <David.Woodhouse@...el.com>
---
Using early-quirks this time, at Andi's suggestion. I haven't been able 
to test this version though, since I killed my board when trying to reflash 
the BIOS too many times. Arjan, did you say we have a pile of these?

 arch/x86/kernel/early-quirks.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 4353cf5..f51f61b 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -95,6 +95,20 @@ static void __init nvidia_bugs(int num, int slot, int func)
 
 }
 
+#ifdef CONFIG_DMAR
+static void __init intel_g33_dmar(int num, int slot, int func)
+{
+	struct acpi_table_header *dmar_tbl;
+	acpi_status = status;
+
+	status = acpi_get_table(ACPI_SIG_DMAR, 0, &dmar_tbl);
+	if (ACPI_SUCCESS(status)) {
+		printk(KERN_INFO "BIOS BUG: DMAR advertised on Intel G31/G33 chipset -- ignoring\n");
+		dmar_disabled = 1;
+	}
+}
+#endif
+
 #define QFLAG_APPLY_ONCE 	0x1
 #define QFLAG_APPLIED		0x2
 #define QFLAG_DONE		(QFLAG_APPLY_ONCE|QFLAG_APPLIED)
@@ -114,6 +128,10 @@ static struct chipset early_qrk[] __initdata = {
 	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, via_bugs },
 	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB,
 	  PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, fix_hypertransport_config },
+#ifdef CONFIG_DMAR
+	{ PCI_VENDOR_ID_INTEL, 0x29c0,
+	  PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, intel_g33_dmar },
+#endif
 	{}
 };
 
-- 
1.5.5.1
-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@...el.com                              Intel Corporation



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