UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

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>
This commit is contained in:
Mike Habeck 2010-05-12 11:14:32 -07:00 committed by Jesse Barnes
parent 549e15611b
commit 7bd1c365fd
3 changed files with 23 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/kernel-parameters.txt
View File

@ -1970,6 +1970,8 @@ and is between 256 and 4096 characters. It is defined in the file
norom [X86] Do not assign address space to
expansion ROMs that do not already have
BIOS assigned address ranges.
nobar [X86] Do not assign address space to the
BARs that weren't assigned by the BIOS.
irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
assigned automatically to PCI devices. You can
make the kernel exclude IRQs of your ISA cards

1
arch/x86/include/asm/pci_x86.h
View File

@ -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;

20
arch/x86/pci/common.c
View File

@ -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;