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authorMike Habeck <habeck@sgi.com>2010-05-12 11:14:32 -0700
committerJesse Barnes <jbarnes@virtuousgeek.org>2010-07-30 09:29:12 -0700
commit7bd1c365fd124624191d49dcc1eb9759d6017ec3 (patch)
tree3e193b2061e02f4e04c51d14ce7a066c6e850bb2 /arch/x86
parent549e15611b4ac1de51ef0e0a79c2704f50a638a2 (diff)
downloadop-kernel-dev-7bd1c365fd124624191d49dcc1eb9759d6017ec3.zip
op-kernel-dev-7bd1c365fd124624191d49dcc1eb9759d6017ec3.tar.gz
x86/PCI: Add option to not assign BAR's if not already assigned
The Linux kernel assigns BARs that a BIOS did not assign, most likely to handle broken BIOSes that didn't enumerate the devices correctly. On UV the BIOS purposely doesn't assign I/O BARs for certain devices/ drivers we know don't use them (examples, LSI SAS, Qlogic FC, ...). We purposely don't assign these I/O BARs because I/O Space is a very limited resource. There is only 64k of I/O Space, and in a PCIe topology that space gets divided up into 4k chucks (this is due to the fact that a pci-to-pci bridge's I/O decoder is aligned at 4k)... Thus a system can have at most 16 cards with I/O BARs: (64k / 4k = 16) SGI needs to scale to >16 devices with I/O BARs. So by not assigning I/O BARs on devices we know don't use them, we can do that (iff the kernel doesn't go and assign these BARs that the BIOS purposely didn't assign). This patch will not assign a resource to a device BAR if that BAR was not assigned by the BIOS, and the kernel cmdline option 'pci=nobar' was specified. This patch is closely modeled after the 'pci=norom' option that currently exists in the tree. Signed-off-by: Mike Habeck <habeck@sgi.com> Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/pci_x86.h1
-rw-r--r--arch/x86/pci/common.c20
2 files changed, 21 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index cd2a31d..49c7219 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -30,6 +30,7 @@
#define PCI_HAS_IO_ECS 0x40000
#define PCI_NOASSIGN_ROMS 0x80000
#define PCI_ROOT_NO_CRS 0x100000
+#define PCI_NOASSIGN_BARS 0x200000
extern unsigned int pci_probe;
extern unsigned long pirq_table_addr;
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 215a27a..a0772af 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -125,6 +125,23 @@ void __init dmi_check_skip_isa_align(void)
static void __devinit pcibios_fixup_device_resources(struct pci_dev *dev)
{
struct resource *rom_r = &dev->resource[PCI_ROM_RESOURCE];
+ struct resource *bar_r;
+ int bar;
+
+ if (pci_probe & PCI_NOASSIGN_BARS) {
+ /*
+ * If the BIOS did not assign the BAR, zero out the
+ * resource so the kernel doesn't attmept to assign
+ * it later on in pci_assign_unassigned_resources
+ */
+ for (bar = 0; bar <= PCI_STD_RESOURCE_END; bar++) {
+ bar_r = &dev->resource[bar];
+ if (bar_r->start == 0 && bar_r->end != 0) {
+ bar_r->flags = 0;
+ bar_r->end = 0;
+ }
+ }
+ }
if (pci_probe & PCI_NOASSIGN_ROMS) {
if (rom_r->parent)
@@ -509,6 +526,9 @@ char * __devinit pcibios_setup(char *str)
} else if (!strcmp(str, "norom")) {
pci_probe |= PCI_NOASSIGN_ROMS;
return NULL;
+ } else if (!strcmp(str, "nobar")) {
+ pci_probe |= PCI_NOASSIGN_BARS;
+ return NULL;
} else if (!strcmp(str, "assign-busses")) {
pci_probe |= PCI_ASSIGN_ALL_BUSSES;
return NULL;
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