• Yinghai Lu's avatar
    x86: Add Crash kernel low reservation · 0212f915
    Yinghai Lu authored
    During kdump kernel's booting stage, it need to find low ram for
    swiotlb buffer when system does not support intel iommu/dmar remapping.
    
    kexed-tools is appending memmap=exactmap and range from /proc/iomem
    with "Crash kernel", and that range is above 4G for 64bit after boot
    protocol 2.12.
    
    We need to add another range in /proc/iomem like "Crash kernel low",
    so kexec-tools could find that info and append to kdump kernel
    command line.
    
    Try to reserve some under 4G if the normal "Crash kernel" is above 4G.
    
    User could specify the size with crashkernel_low=XX[KMG].
    
    -v2: fix warning that is found by Fengguang's test robot.
    -v3: move out get_mem_size change to another patch, to solve compiling
         warning that is found by Borislav Petkov <bp@alien8.de>
    -v4: user must specify crashkernel_low if system does not support
         intel or amd iommu.
    Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
    Link: http://lkml.kernel.org/r/1359058816-7615-31-git-send-email-yinghai@kernel.org
    Cc: Eric Biederman <ebiederm@xmission.com>
    Cc: Rob Landley <rob@landley.net>
    Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
    0212f915
kexec.c 40.3 KB