• Terry Loftin's avatar
    [IA64] use machvec=dig on hpzx1 platforms · 51b58e3e
    Terry Loftin authored
    On HP zx1 machines, the 'machvec=dig' parameter is needed for the
    kdump kernel to avoid problems with the HP sba iommu.  The problem
    is that during the boot of the kdump kernel, the iommu is re-initialized,
    so in-flight DMA from improperly shutdown drivers causes an IOTLB
    miss which leads to an MCA.  With kdump, the idea is to get into the
    kdump kernel with as little code as we can, so shutting down drivers
    properly is not an option.
    
    The workaround is to add 'machvec=dig' to the kdump kernel boot
    parameters.  This makes the kdump kernel avoid using the sba iommu
    altogether, leaving the IOTLB intact.  Any ongoing DMA falls
    harmlessly outside the kdump kernel.  After the kdump kernel reboots,
    all devices will have been shutdown properly and DMA stopped.
    
    This patch pushes that functionality into the sba iommu
    initialization code, so that users won't have to find the obscure
    documentation telling them about 'machvec=dig'.
    
    This patch only affects HP platforms.  It still includes one
    extern declaration in the file, because no applicable header file
    exists.
    Signed-off-by: default avatarTerry Loftin <terry.loftin@hp.com>
    Signed-off-by: default avatarAlex Williamson <alex.williamson@hp.com>
    Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
    51b58e3e
sba_iommu.c 56 KB