[RFC PATCH v2 08/11] powerpc: gamecube/wii: early debugging using usbgecko
albert_herranz at yahoo.es
Mon Nov 30 17:15:42 EST 2009
Albert Herranz wrote:
> Benjamin Herrenschmidt wrote:
>> On Sat, 2009-11-28 at 21:43 +0100, Albert Herranz wrote:
>>> + * Prepare again the same BAT for MMU_init.
>>> + * This allows udbg I/O to continue working after the MMU is
>>> + * turned on for real.
>>> + *
>>> + * We are assuming here that exi_io_base is identity mapped.
>>> + */
>>> + addr = ((unsigned long)exi_io_base) & 0xffff0000;
>>> + setbat(1, addr, addr, 128*1024, PAGE_KERNEL_NCG);
>> How do you prevent that from overlapping otherwise valid kernel
>> mappings ?
> ug_udbg_init() is called from ppc_md.init_early.
This got here, but although it's true it doesn't apply here :)
> It doesn't overlap any valid kernel mappings because exi_io_base is hardcoded to an i/o region not used yet by the kernel.
> See udbg_early_grab_exi_io_base().
> The setbat just prepares again, exactly in the same way, the same BAT that we got setup by setup_usbgecko_bat in head_32.S.
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