1 GB lowmem

[Rune Torgersen]

Rune Torgersen wrote:
> linuxppc-dev-bounces+runet=innovsys.com at ozlabs.org wrote:
>> Hi
>> 
>> I am trying to enable 1 GB of lowmem on a Freescale 8280.
>> In arch/ppc this was easilly done by:
>> CONFIG_ADVANCED_OPTIONS=y
>> CONFIG_HIGHMEM_START=0xfe000000
>> CONFIG_LOWMEM_SIZE_BOOL=y
>> CONFIG_LOWMEM_SIZE=0x40000000
>> CONFIG_KERNEL_START_BOOL=y
>> CONFIG_KERNEL_START=0xa0000000
>> 
>> This does not work in arch/powerpc. CPU hangs as soon as init starts.
>> Any ideas what to look at, what to change?
>> 
>> The reason I want to do this is because I cannot get highmem support
>> to work when using CONFIG_PREEMPT_RT.
>> (hitting a bug_on in kmap_atomic)
> 
> Scratch that. 1 GB lowmem works with vanilla 2.6.25.4, but
> not at all with 2.6.25.4-rt[13]

Argh... Found it. Had to set CONFIG_TASK_SIZE to 0x80000000. Now it
works in both vaniulla an d RT kernel.
Highmem still doesn't work.