lkml.org 
[lkml]   [2011]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    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
    head.S.

    > 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
    exposing.

    > 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.


    Nicolas


    \
     
     \ /
      Last update: 2011-01-12 17:55    [W:0.022 / U:0.236 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site