• David Brownell's avatar
    target.cfg: remove "-work-area-virt 0" · 3e6f9e8d
    David Brownell authored
    
    
    The semantics of "-work-area-virt 0" (or phys) changed with
    the patch to require specifying physical or virtrual work
    area addresses.  Specifying zero was previously a NOP.  Now
    it means that address zero is valid.
    
    This patch addresses three related issues:
    
     - MMU-less processors should never specify work-area-virt;
       remove those specifications.  Such processors include
       ARM7TDMI, Cortex-M3, and ARM966.
    
     - MMU-equipped processors *can* specify work-area-virt...
       but zero won't be appropriate, except in mischievous
       contexts (which hide null pointer exceptions).
    
       Remove those specs from those processors too.  If any of
       those mappings is valid, someone will need to submit a
       patch adding it ... along with a comment saying what OS
       provides the mapping, and in which context.  Example,
       say "works with Linux 2.6.30+, in kernel mode".  (Note
       that ARM Linux doesn't map kernel memory to zero ...)
    
     - Clarify docs on that "-virt" and other work area stuff.
    
    Seems to me work-area-virt is quite problematic; not every
    operating system provides such static mappings; if they do,
    they're not in every MMU context...
    
    Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
    3e6f9e8d