arm cortex a9, smp bootup requirement

arm cortex a9, smp bootup requirement

[Michal Simek]

Hi,

can someone correct me about smp boot requirement for Linux?

We are fixing ARM zynq smp bootup code and would like to be sure
that out bootup code is correct.

I have found some requirements from standalone boot up code
which is invalidate dcache, icache, branch predictor array
and flush TLB.

I have found in secondary_start_kernel that TLB are flushed
by local_flush_tlb_all function.
But haven't found any cache invalidation calling.

I think it is required and we could be added to platform_secondary_init.

Or is it requirement which has to be fulfil by bootloader before
secondary_startup is called?

We have the option to reset specific cpu in the system and cpu
starts from 0x0 with cache off and in non-virtual mode
where we place simple jump trampoline to the secondary_startup
function. If cache invalidation is required by Linux we can extend this code
to do it.

Jumping trampoline is:
0x0: ldr r0, [8]
0x4: mov pc, r0
0x8: jump address

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian

arm cortex a9, smp bootup requirement

[Michal Simek]

Hi,

can someone correct me about smp boot requirement for Linux?

We are fixing ARM zynq smp bootup code and would like to be sure
that out bootup code is correct.

I have found some requirements from standalone boot up code
which is invalidate dcache, icache, branch predictor array
and flush TLB.

I have found in secondary_start_kernel that TLB are flushed
by local_flush_tlb_all function.
But haven't found any cache invalidation calling.

I think it is required and we could be added to platform_secondary_init.

Or is it requirement which has to be fulfil by bootloader before
secondary_startup is called?

We have the option to reset specific cpu in the system and cpu
starts from 0x0 with cache off and in non-virtual mode
where we place simple jump trampoline to the secondary_startup
function. If cache invalidation is required by Linux we can extend this code
to do it.

Jumping trampoline is:
0x0: ldr r0, [8]
0x4: mov pc, r0
0x8: jump address

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian