• Mike Westerhof's avatar
    [ARM] 4599/1: Preserve ATAG list for use with kexec (2.6.23) · 033b8ffe
    Mike Westerhof authored
    This patch resolves a kexec boot failure that can occur because
    no ATAGs are passed in to the kexec'd kernel. Currently the
    newly-kexec'd kernel may fail if it requires specific ATAGs, or
    it may fail because the fixed memory location at which it expects
    to find the ATAGs may contain random data instead of ATAGs.
    
    The patch ensures that any ATAGs passed to the current kernel
    at boot time are copied to a static buffer, and are copied back
    when kexec copies the new kernel into place. Thus the new
    kernel sees the same ATAGs from kexec and the boot loader.
    
    The boot parameters are copied without regard to type, content,
    or length -- this patch's scope is limited soley to saving and
    restoring a fixed-size block of memory containing the kernel's
    boot parameters. Additional functionality to examine, alter, or
    replace the ATAGs (using kexec, for example) can be implemented
    by manipulating the static buffer containing the preserved ATAGs.
    
    Note: the size of the buffer (1.5KB) is selected to comfortably
    hold one of each ATAG type, including a maximum-length command
    line and the maximum number of ATAG_MEM structures currently
    supported by the kernel. Should an ATAG list exceed that limit,
    the list will be silently truncated to that limit (to do other-
    wise at that point in the boot process would make a simple
    problem exceedingly complicated).
    
    [Note: this is the same patch as 4579, modified to accomodate
    the ATAG changes introduced in 2.6.23]
    
    Signed-off-by: Mike Westerhof <mwester at dls.net>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    033b8ffe
relocate_kernel.S 1.63 KB