Attachment 586713 Details for Bug 825036 – Upstream patch adding nobar cmdline argument

[patch] Upstream patch adding nobar cmdline argument

nobar.patch (text/plain), 3.72 KB, created by George Beshers on 2012-05-24 21:30:53 UTC

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Creator: George Beshers

Created: 2012-05-24 21:30:53 UTC

Size: 3.72 KB

patch

obsolete

>commit 7bd1c365fd124624191d49dcc1eb9759d6017ec3
>Author: Mike Habeck <habeck@sgi.com>
>Date:   Wed May 12 11:14:32 2010 -0700
>
>    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>
>
>diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>index 2b2407d..4fac69b 100644
>--- a/Documentation/kernel-parameters.txt
>+++ b/Documentation/kernel-parameters.txt
>@@ -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
>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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Attachments on bug 825036: 586713