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    SubjectRe: [RFC] arm: Defer lookup of machine_type and vet of atags to setup.c
    On Wed, 12 Jan 2011, Grant Likely wrote:

    > Actually it looks like the real problem is that the mmu has been
    > turned on, but the virtual mappings for devices have not yet been
    > established, and so the debug macros aren't using a valid address.

    A temporary virtual mapping should be there -- look for addruart in

    > I'm using printk to get output into the ring buffer in my patch to
    > rework lookup_machine_type() in C, and that does indeed output to the
    > ring buffer, but the kernel cannot spit stuff out the serial port.
    > It looks like I'd need to get past paging_init() in order to get
    > ll_debug working between turning on the mmu and paging_init(), but
    > paging_init() needs the mdesc pointer, and the whole point of the
    > error message is that the mdesc pointer is unknown! I don't see any
    > code that sets up a debug mapping of the uart before paging_init time.

    See above.

    > I could try to implement something like that, but it is looking to be
    > more complicated than it is worth when the current code works just
    > fine.

    My bet is that there is a bug with the current code that you are

    > Let me know if I've missed something, but I think I should drop the
    > removal of __lookup_machine_type from head.S from my patch.

    It's not the location of that code which is a problem. Even if you
    leave that code in place, you want to call it later and I bet that the
    display would be broken even if __lookup_machine_type doesn't move.


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      Last update: 2011-01-12 17:55    [W:0.020 / U:8.076 seconds]
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