• Yinghai Lu's avatar
    x86: reserve dma32 early for gart · f62f1fc9
    Yinghai Lu authored
    a system with 256 GB of RAM, when NUMA is disabled crashes the
    following way:
    
    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
    Cannot allocate aperture memory hole (ffff8101c0000000,65536K)
    Kernel panic - not syncing: Not enough memory for aperture
    Pid: 0, comm: swapper Not tainted 2.6.25-rc4-x86-latest.git #33
    
    Call Trace:
     [<ffffffff84037c62>] panic+0xb2/0x190
     [<ffffffff840381fc>] ? release_console_sem+0x7c/0x250
     [<ffffffff847b1628>] ? __alloc_bootmem_nopanic+0x48/0x90
     [<ffffffff847b0ac9>] ? free_bootmem+0x29/0x50
     [<ffffffff847ac1f7>] gart_iommu_hole_init+0x5e7/0x680
     [<ffffffff847b255b>] ? alloc_large_system_hash+0x16b/0x310
     [<ffffffff84506a2f>] ? _etext+0x0/0x1
     [<ffffffff847a2e8c>] pci_iommu_alloc+0x1c/0x40
     [<ffffffff847ac795>] mem_init+0x45/0x1a0
     [<ffffffff8479ff35>] start_kernel+0x295/0x380
     [<ffffffff8479f1c2>] _sinittext+0x1c2/0x230
    
    the root cause is : memmap PMD is too big,
    [ffffe200e0600000-ffffe200e07fffff] PMD ->ffff81383c000000 on node 0
    almost near 4G..., and vmemmap_alloc_block will use up the ram under 4G.
    
    solution will be:
    1. make memmap allocation get memory above 4G...
    2. reserve some dma32 range early before we try to set up memmap for all.
    and release that before pci_iommu_alloc, so gart or swiotlb could get some
    range under 4g limit for sure.
    
    the patch is using method 2.
    because method1 may need more code to handle SPARSEMEM and SPASEMEM_VMEMMAP
    
    will get
    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
    Memory: 264245736k/268959744k available (8484k kernel code, 4187464k reserved, 4004k data, 724k init)
    Signed-off-by: default avatarYinghai Lu <yhlu.kernel@gmail.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    f62f1fc9
setup_64.c 29 KB