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    kexec: create a new config option CONFIG_KEXEC_FILE for new syscall · 74ca317c
    Vivek Goyal 提交于
    Currently new system call kexec_file_load() and all the associated code
    compiles if CONFIG_KEXEC=y.  But new syscall also compiles purgatory
    code which currently uses gcc option -mcmodel=large.  This option seems
    to be available only gcc 4.4 onwards.
    
    Hiding new functionality behind a new config option will not break
    existing users of old gcc.  Those who wish to enable new functionality
    will require new gcc.  Having said that, I am trying to figure out how
    can I move away from using -mcmodel=large but that can take a while.
    
    I think there are other advantages of introducing this new config
    option.  As this option will be enabled only on x86_64, other arches
    don't have to compile generic kexec code which will never be used.  This
    new code selects CRYPTO=y and CRYPTO_SHA256=y.  And all other arches had
    to do this for CONFIG_KEXEC.  Now with introduction of new config
    option, we can remove crypto dependency from other arches.
    
    Now CONFIG_KEXEC_FILE is available only on x86_64.  So whereever I had
    CONFIG_X86_64 defined, I got rid of that.
    
    For CONFIG_KEXEC_FILE, instead of doing select CRYPTO=y, I changed it to
    "depends on CRYPTO=y".  This should be safer as "select" is not
    recursive.
    Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
    Cc: Eric Biederman <ebiederm@xmission.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Tested-by: NShaun Ruffell <sruffell@digium.com>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    74ca317c
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