lkml.org 
[lkml]   [2010]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[PATCH v3 4/6] x86/PCI: allocate space from the end of a region, not the beginning
    From
    Date

    Allocate from the end of a region, not the beginning.

    For example, if we need to allocate 0x800 bytes for a device on bus
    0000:00 given these resources:

    [mem 0xbff00000-0xdfffffff] PCI Bus 0000:00
    [mem 0xc0000000-0xdfffffff] PCI Bus 0000:02

    the available space at [mem 0xbff00000-0xbfffffff] is passed to the
    alignment callback (pcibios_align_resource()). Prior to this patch, we
    would put the new 0x800 byte resource at the beginning of that available
    space, i.e., at [mem 0xbff00000-0xbff007ff].

    With this patch, we put it at the end, at [mem 0xbffff800-0xbfffffff].

    Reference: https://bugzilla.kernel.org/show_bug.cgi?id=16228#c41
    Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
    ---

    arch/x86/pci/i386.c | 18 ++++++++++++------
    1 files changed, 12 insertions(+), 6 deletions(-)


    diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
    index 5525309..fe866c8 100644
    --- a/arch/x86/pci/i386.c
    +++ b/arch/x86/pci/i386.c
    @@ -37,6 +37,7 @@
    #include <asm/pci_x86.h>
    #include <asm/io_apic.h>

    +#define ALIGN_DOWN(x, a) ((x) & ~(a - 1))

    static int
    skip_isa_ioresource_align(struct pci_dev *dev) {
    @@ -65,16 +66,21 @@ pcibios_align_resource(void *data, const struct resource *res,
    resource_size_t size, resource_size_t align)
    {
    struct pci_dev *dev = data;
    - resource_size_t start = res->start;
    + resource_size_t start = ALIGN_DOWN(res->end - size + 1, align);

    if (res->flags & IORESOURCE_IO) {
    - if (skip_isa_ioresource_align(dev))
    - return start;
    - if (start & 0x300)
    - start = (start + 0x3ff) & ~0x3ff;
    +
    + /*
    + * If we're avoiding ISA aliases, the largest contiguous I/O
    + * port space is 256 bytes. Clearing bits 9 and 10 preserves
    + * all 256-byte and smaller alignments, so the result will
    + * still be correctly aligned.
    + */
    + if (!skip_isa_ioresource_align(dev))
    + start &= ~0x300;
    } else if (res->flags & IORESOURCE_MEM) {
    if (start < BIOS_END)
    - start = BIOS_END;
    + start = res->end; /* fail; no space */
    }
    return start;
    }


    \
     
     \ /
      Last update: 2010-10-13 18:17    [W:0.028 / U:0.020 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site