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    SubjectRe: [PATCH] PCI: boot parameter to avoid expansion ROM memory allocation
    On Tue, May 13, 2008 at 2:00 PM, Gary Hade <garyhade@us.ibm.com> wrote:
    >
    > On Tue, May 13, 2008 at 10:48:03AM -0700, Yinghai Lu wrote:
    > > On Mon, May 12, 2008 at 3:30 PM, Gary Hade <garyhade@us.ibm.com> wrote:
    > > > On Mon, May 12, 2008 at 02:43:44PM -0700, Yinghai Lu wrote:
    > > > > On Mon, May 12, 2008 at 1:57 PM, Gary Hade <garyhade@us.ibm.com> wrote:
    > > > <snip>
    > > >
    > > > > > --- linux-2.6.26-rc2/arch/x86/pci/common.c.orig 2008-05-12 10:59:58.000000000 -0700
    > > > > > +++ linux-2.6.26-rc2/arch/x86/pci/common.c 2008-05-12 11:22:05.000000000 -0700
    > > > > > @@ -121,6 +121,21 @@ void __init dmi_check_skip_isa_align(voi
    > > > > > dmi_check_system(can_skip_pciprobe_dmi_table);
    > > > > > }
    > > > > >
    > > > > > +static void __devinit pcibios_fixup_device_resources(struct pci_dev *dev)
    > > > > > +{
    > > > > > + struct resource *rom_r = &dev->resource[PCI_ROM_RESOURCE];
    > > > > > +
    > > > > > + if (pci_probe & PCI_NOASSIGN_ROMS) {
    > > > > > + if (rom_r->parent)
    > > > > > + return;
    > > > > > + if (rom_r->start) {
    > > > > > + /* we deal with BIOS assigned ROM later */
    > > > > > + return;
    > > > > > + }
    > > > > > + rom_r->start = rom_r->end = rom_r->flags = 0;
    > > > > > + }
    > > > > > +}
    > > > > > +
    > > > > > /*
    > > > > > * Called after each bus is probed, but before its children
    > > > > > * are examined.
    > > > > > @@ -128,7 +143,11 @@ void __init dmi_check_skip_isa_align(voi
    > > > > >
    > > > > > void __devinit pcibios_fixup_bus(struct pci_bus *b)
    > > > > > {
    > > > > > + struct pci_dev *dev;
    > > > > > +
    > > > > > pci_read_bridge_bases(b);
    > > > > > + list_for_each_entry(dev, &b->devices, bus_list)
    > > > > > + pcibios_fixup_device_resources(dev);
    > > > > > }
    > > > >
    > > > > or put check
    > > > > + if (pci_probe & PCI_NOASSIGN_ROMS) {
    > > > >
    > > > > out of loop?
    > > >
    > > > I could certainly do that but I had intended that the new
    > > > pcibios_fixup_device_resources function act as a container where
    > > > other kinds of fixups could be added later. Do you (or others)
    > > > think the additional cycles consumed by this approach are an
    > > > issue here?
    > >
    > > ok, then wonder if we can don't assign roms for x86_64 by default.
    >
    > No, I don't think so. ..at least not by me! :)
    >
    > There were some lkml/linux-pci visible discussions back in
    > November-December of last year where I floated the idea
    > of making PCI expansion ROM memory non-assignment the default:
    > http://marc.info/?l=linux-kernel&m=119742188215024&w=2
    > http://marc.info/?l=linux-kernel&m=119689499508369&w=2
    > I did not hear any objections so I went ahead and submitted
    > the change which entered mainline at 2.6.25-rc1 but it was
    > sternly evicted last week because of a reported regression
    > that it had caused:
    > http://marc.info/?l=linux-kernel&m=121029093331908&w=2
    > Attachments to http://bugs.freedesktop.org/show_bug.cgi?id=15523
    > indicate that a 2.6.25-rc2 x86_64 kernel was being used.
    >
    >
    > >
    > > can we use pci rom in 64 bit kernel?
    >
    > Sorry, not sure if I understand this question. I hope the
    > above answers it.

    ok, i think the driver could reload fw in the option rom to reset the
    controlller in pci card.
    i don't think there is other usage for the option rom after OS loaded,
    except option rom contain other run-time code...

    so could disable them all, and use pci-quirks to enable that for the
    device/driver need it.

    YH


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