From: Konrad Rzeszutek <konradr@redhat.com>
Subject: [RHEL5 PATCH] #220078 -allow compiling Calgary in but not using it by default
Date: Mon, 18 Dec 2006 15:57:18 -0500
Bugzilla: 220078
Message-Id: <20061218205718.GA27037@dhcp83-154.boston.redhat.com>
Changelog: x86_64: create Calgary boot knob


RHBZ#:
------
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=220078

Description:
------------
The Calgary IOMMU and the newer version of Calgary2 chipsets 
are not working with RHEL5. RHEL5 panics at bootup.

Main-line is working on resolving this issue (adding new code
for the chipset) but in the meantime, we do have a patch from 
main-line (2.6.20-rc1) which provides a bootup knob to turn 
Calgary on if the customer wants it (and a compile flag).


RHEL Version Found:
------------------
RHEL5 RC1 snaphost 1

Upstream Status:
----------------
In 2.6.20-rc1

Test Status:
------------
Tested on x460 in Westford for regression - no trouble. It was
tested on the x460 in Beaverton with the Tulsa procs (and the newer Calgary).

Proposed Patch:
---------------
This patch is based on 2.6.18-1.2901 kernel.

Also a compile flag needs to be added:

# CALGARY_IOMMU_ENABLED_BY_DEFAULT is not set

to the config files.

diff -uNr linux-2.6.18.i386.orig/arch/x86_64/Kconfig linux-2.6.18.i386/arch/x86_64/Kconfig
--- linux-2.6.18.i386.orig/arch/x86_64/Kconfig	2006-12-18 11:21:25.000000000 -0500
+++ linux-2.6.18.i386/arch/x86_64/Kconfig	2006-12-18 11:23:22.000000000 -0500
@@ -481,6 +481,17 @@
 	  Normally the kernel will make the right choice by itself.
 	  If unsure, say Y.
 
+config CALGARY_IOMMU_ENABLED_BY_DEFAULT
+	bool "Should Calgary be enabled by default?"
+	default n
+	depends on CALGARY_IOMMU
+	help
+	  Should Calgary be enabled by default? if you choose 'y', Calgary
+	  will be used (if it exists). If you choose 'n', Calgary will not be
+	  used even if it exists. If you choose 'n' and would like to use
+	  Calgary anyway, pass 'iommu=calgary' on the kernel command line.
+	  If unsure, say Y.
+
 # need this always selected by IOMMU for the VIA workaround
 config SWIOTLB
 	bool
diff -uNr linux-2.6.18.i386.orig/arch/x86_64/kernel/pci-calgary.c linux-2.6.18.i386/arch/x86_64/kernel/pci-calgary.c
--- linux-2.6.18.i386.orig/arch/x86_64/kernel/pci-calgary.c	2006-12-18 11:21:25.000000000 -0500
+++ linux-2.6.18.i386/arch/x86_64/kernel/pci-calgary.c	2006-12-18 12:57:54.000000000 -0500
@@ -41,6 +41,12 @@
 #include <asm/system.h>
 #include <asm/dma.h>
 
+#ifdef CONFIG_CALGARY_IOMMU_ENABLED_BY_DEFAULT
+int use_calgary __read_mostly = 1;
+#else
+int use_calgary __read_mostly = 0;
+#endif /* CONFIG_CALGARY_DEFAULT_ENABLED */
+
 #define PCI_DEVICE_ID_IBM_CALGARY 0x02a1
 #define PCI_VENDOR_DEVICE_ID_CALGARY \
 	(PCI_VENDOR_ID_IBM | PCI_DEVICE_ID_IBM_CALGARY << 16)
@@ -898,6 +904,13 @@
 	if (swiotlb || no_iommu || iommu_detected)
 		return;
 
+	/*
+	 * If the user did not specify iommu=calgary 
+	 * (and CALGARY_IOMMU_ENABLED_BY_DEFAULT=n), bail out.
+	 */
+	if (!use_calgary)
+		return;
+
 	specified_table_size = determine_tce_table_size(end_pfn * PAGE_SIZE);
 
 	for (bus = 0; bus < MAX_PHB_BUS_NUM; bus++) {
diff -uNr linux-2.6.18.i386.orig/arch/x86_64/kernel/pci-dma.c linux-2.6.18.i386/arch/x86_64/kernel/pci-dma.c
--- linux-2.6.18.i386.orig/arch/x86_64/kernel/pci-dma.c	2006-12-18 11:21:25.000000000 -0500
+++ linux-2.6.18.i386/arch/x86_64/kernel/pci-dma.c	2006-12-18 11:48:00.000000000 -0500
@@ -274,6 +274,11 @@
 	    gart_parse_options(p);
 #endif
 
+#ifdef CONFIG_CALGARY_IOMMU
+	    if (!strncmp(p, "calgary", 7))
+		    use_calgary = 1;
+#endif /* CONFIG_CALGARY_IOMMU */
+
 	    p += strcspn(p, ",");
 	    if (*p == ',')
 		    ++p;
diff -uNr linux-2.6.18.i386.orig/Documentation/x86_64/boot-options.txt linux-2.6.18.i386/Documentation/x86_64/boot-options.txt
--- linux-2.6.18.i386.orig/Documentation/x86_64/boot-options.txt	2006-12-18 11:21:28.000000000 -0500
+++ linux-2.6.18.i386/Documentation/x86_64/boot-options.txt	2006-12-18 11:43:22.000000000 -0500
@@ -183,7 +183,7 @@
 IOMMU
 
  iommu=[size][,noagp][,off][,force][,noforce][,leak][,memaper[=order]][,merge]
-         [,forcesac][,fullflush][,nomerge][,noaperture]
+         [,forcesac][,fullflush][,nomerge][,noaperture][,calgary]
    size  set size of iommu (in bytes)
    noagp don't initialize the AGP driver and use full aperture.
    off   don't use the IOMMU
@@ -199,6 +199,7 @@
    allowed  overwrite iommu off workarounds for specific chipsets.
    soft	 Use software bounce buffering (default for Intel machines)
    noaperture Don't touch the aperture for AGP.
+   calgary Use the Calgary IOMMU if it is available
 
   swiotlb=pages[,force]
 
diff -uNr linux-2.6.18.i386.orig/include/asm-x86_64/calgary.h linux-2.6.18.i386/include/asm-x86_64/calgary.h
--- linux-2.6.18.i386.orig/include/asm-x86_64/calgary.h	2006-12-18 11:21:23.000000000 -0500
+++ linux-2.6.18.i386/include/asm-x86_64/calgary.h	2006-12-18 11:23:22.000000000 -0500
@@ -51,6 +51,8 @@
 #define TCE_TABLE_SIZE_4M		6
 #define TCE_TABLE_SIZE_8M		7
 
+extern int use_calgary;
+
 #ifdef CONFIG_CALGARY_IOMMU
 extern int calgary_iommu_init(void);
 extern void detect_calgary(void);

-- 
Konrad Rzeszutek 1-(978)-392-3903 or 1-(617)-693-1718
IBM on-site partner.