Re: Regression: 2.6.34 boot fails on E5405 system, bisected: de08e2c26

[Ben Greear]

On 07/14/2010 11:52 AM, H. Peter Anvin wrote:
> So I suggest the following changes...
>
> On 07/13/2010 07:19 PM, Jesse Barnes wrote:
> > > static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn)
> > > {
> > > 	int pos;
> > > 	u32 pcie_cap = 0, cap_data;
> > > 	printk("fixed_bar_cap, bus: %p  devfn: %u\n", bus, devfn);
> > > 	pos = PCIE_CAP_OFFSET;
> > > 	while (pos) {
>
> while (pos>= PCIE_CAP_OFFSET) {
>
> > > 		printk("Before read..\n");
> > > 		if (raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
> > > 					  devfn, pos, 4,&pcie_cap))
> > > 			return 0;
> > > 		printk("pcie_cap: %u", pcie_cap);
> > > 		
>     -		if (pcie_cap == 0xffffffff)
>     -			return 0;
> 		
>     +		if (PCI_EXT_CAP_ID(pcie_cap) == 0x0000 ||
>     +		    PCI_EXT_CAP_ID(pcie_cap) == 0xffff)
>     +			break;

This seems to work for me.  I'm using this patch against
2.6.34.y:

diff --git a/arch/x86/pci/mrst.c b/arch/x86/pci/mrst.c
index 1cdc02c..ee93fd0 100644
--- a/arch/x86/pci/mrst.c
+++ b/arch/x86/pci/mrst.c
@@ -61,13 +61,14 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn)
        if (!raw_pci_ext_ops)
                return 0;

-       while (pos) {
+       while (pos >= PCIE_CAP_OFFSET) {
                if (raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
                                          devfn, pos, 4, &pcie_cap))
                        return 0;

-               if (pcie_cap == 0xffffffff)
-                       return 0;
+               if (PCI_EXT_CAP_ID(pcie_cap) == 0x0000 ||
+                   PCI_EXT_CAP_ID(pcie_cap) == 0xffff)
+                       break;

                if (PCI_EXT_CAP_ID(pcie_cap) == PCI_EXT_CAP_ID_VNDR) {
                        raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
@@ -76,7 +77,7 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn)
                                return pos;
                }

-               pos = pcie_cap >> 20;
+               pos = (pcie_cap >> 20) & 0xffc;
        }

        return 0;


Thanks,
Ben


> 		
> > > 		printk("Checking vendor..\n");
>
> > > 		if (PCI_EXT_CAP_ID(pcie_cap) == PCI_EXT_CAP_ID_VNDR) {
> > > 			printk("reading domain_nr\n");
> > > 			raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
> > > 					      devfn, pos + 4, 4,&cap_data);
> > > 			printk("cap_data: %u\n", cap_data);
> > > 			if ((cap_data&  0xffff) == PCIE_VNDR_CAP_ID_FIXED_BAR)
> > > 				return pos;
> > > 		}
> > >
> > > 		pos = pcie_cap>>  20;
>
> 		pos = (pcie_cap>>  20)&  0xffc;
>
> > > 		printk("pos after shift: %i\n", pos);
> > > 	}
> > >
> > > 	printk("Returning from fixed_bar_cap\n");
> > > 	return 0;
> > > }
> >
> > I thought a related bug was fixed already; the code should be returning
> > all zeros for non-existent BAR reads.
>
> --
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--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com

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