[PATCH] x86_64: agp_gart size checking for buggy device - Kernel

This is a discussion on [PATCH] x86_64: agp_gart size checking for buggy device - Kernel ; while lookin Rafael J. Wysocki system boot log, find some funny print out Node 0: aperture @ de000000 size 32 MB Aperture too small (32 MB) AGP bridge at 00:04:00 Aperture from AGP @ de000000 size 4096 MB (APSIZE 0) ...

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Thread: [PATCH] x86_64: agp_gart size checking for buggy device

  1. [PATCH] x86_64: agp_gart size checking for buggy device


    while lookin Rafael J. Wysocki system boot log,

    find some funny print out

    Node 0: aperture @ de000000 size 32 MB
    Aperture too small (32 MB)
    AGP bridge at 00:04:00
    Aperture from AGP @ de000000 size 4096 MB (APSIZE 0)
    Aperture too small (0 MB)
    Your BIOS doesn't leave a aperture memory hole
    Please enable the IOMMU option in the BIOS setup
    This costs you 64 MB of RAM
    Mapping aperture over 65536 KB of RAM @ 4000000

    ...

    agpgart: Detected AGP bridge 20
    agpgart: Aperture pointing to RAM
    agpgart: Aperture from AGP @ de000000 size 4096 MB
    agpgart: Aperture too small (0 MB)
    agpgart: No usable aperture found.
    agpgart: Consider rebooting with iommu=memaper=2 to get a good aperture.


    it means BIOS allocate correct gart on NB and AGP bridge but because one bug in silicon
    ( the agp bridge report wrong order, it wants 4G instead)
    the kernel will reject that allocation, also becase the size is only 32M. and try to get another
    64M for gart, and late fix_northbridge can not revert that change because it still read
    wrong size from agp bridge.

    So try to double check order from agp bridge, before calling aperture_valid().

    Signed-off-by: Yinghai Lu

    diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
    index 479926d..9f86778 100644
    --- a/arch/x86/kernel/aperture_64.c
    +++ b/arch/x86/kernel/aperture_64.c
    @@ -138,6 +138,7 @@ static __u32 __init read_agp(int num, int slot, int func, int cap, u32 *order)
    int nbits;
    u32 aper_low, aper_hi;
    u64 aper;
    + u32 old_order;

    printk(KERN_INFO "AGP bridge at %02x:%02x:%02x\n", num, slot, func);
    apsizereg = read_pci_config_16(num, slot, func, cap + 0x14);
    @@ -146,6 +147,9 @@ static __u32 __init read_agp(int num, int slot, int func, int cap, u32 *order)
    return 0;
    }

    + /* old_order could be the value from NB gart setting */
    + old_order = *order;
    +
    apsize = apsizereg & 0xfff;
    /* Some BIOS use weird encodings not in the AGPv3 table. */
    if (apsize & 0xff)
    @@ -159,6 +163,16 @@ static __u32 __init read_agp(int num, int slot, int func, int cap, u32 *order)
    aper_hi = read_pci_config(num, slot, func, 0x14);
    aper = (aper_low & ~((1<<22)-1)) | ((u64)aper_hi << 32);

    + /*
    + * some sick chip, APSIZE is 0, it mean it wants 4G
    + * so let double check that order, let trust AMD NB setting
    + */
    + if (aper + (32UL<<(20 + *order)) > 0x100000000UL) {
    + printk(KERN_INFO "Aperture size %u MB (APSIZE %x) is not right, use setting from NB\n",
    + 32 << *order, apsizereg);
    + *order = old_order;
    + }
    +
    printk(KERN_INFO "Aperture from AGP @ %Lx size %u MB (APSIZE %x)\n",
    aper, 32 << *order, apsizereg);

    diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c
    index 9d82045..288d1f5 100644
    --- a/drivers/char/agp/amd64-agp.c
    +++ b/drivers/char/agp/amd64-agp.c
    @@ -312,6 +312,17 @@ static __devinit int fix_northbridge(struct pci_dev *nb, struct pci_dev *agp,
    pci_read_config_dword(agp, 0x10, &aper_low);
    pci_read_config_dword(agp, 0x14, &aper_hi);
    aper = (aper_low & ~((1<<22)-1)) | ((u64)aper_hi << 32);
    +
    + /*
    + * some sick chip, APSIZE is 0, it mean it wants 4G
    + * so let double check that order, let trust AMD NB setting
    + */
    + if (aper + (32UL<<(20 + order)) > 0x100000000UL) {
    + printk(KERN_INFO "Aperture size %u MB is not right, use setting from NB\n",
    + 32 << order);
    + order = nb_order;
    + }
    +
    printk(KERN_INFO PFX "Aperture from AGP @ %Lx size %u MB\n", aper, 32 << order);
    if (order < 0 || !aperture_valid(aper, (32*1024*1024)< return -1;
    --
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  2. Re: [PATCH] x86_64: agp_gart size checking for buggy device


    * Yinghai Lu wrote:

    > So try to double check order from agp bridge, before calling
    > aperture_valid().


    thanks Yinghai, applied!

    Ingo
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