• Simon Horman's avatar
    kdump: add is_vmcore_usable() and vmcore_unusable() · 85a0ee34
    Simon Horman authored
    The usage of elfcorehdr_addr has changed recently such that being set to
    ELFCORE_ADDR_MAX is used by is_kdump_kernel() to indicate if the code is
    executing in a kernel executed as a crash kernel.
    
    However, arch/ia64/kernel/setup.c:reserve_elfcorehdr will rest
    elfcorehdr_addr to ELFCORE_ADDR_MAX on error, which means any subsequent
    calls to is_kdump_kernel() will return 0, even though they should return
    1.
    
    Ok, at this point in time there are no subsequent calls, but I think its
    fair to say that there is ample scope for error or at the very least
    confusion.
    
    This patch add an extra state, ELFCORE_ADDR_ERR, which indicates that
    elfcorehdr_addr was passed on the command line, and thus execution is
    taking place in a crashdump kernel, but vmcore can't be used for some
    reason.  This is tested for using is_vmcore_usable() and set using
    vmcore_unusable().  A subsequent patch makes use of this new code.
    
    To summarise, the states that elfcorehdr_addr can now be in are as follows:
    
    ELFCORE_ADDR_MAX: not a crashdump kernel
    ELFCORE_ADDR_ERR: crashdump kernel but vmcore is unusable
    any other value:  crash dump kernel and vmcore is usable
    Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    85a0ee34
vmcore.c 16.1 KB