[U-Boot] [PATCH 3/8] sun8i: Extend stack size to allow for up to 8 CPUs

[Chen-Yu Tsai]

On Wed, May 18, 2016 at 3:19 AM, Timothy Pearson
<tpearson at raptorengineering.com> wrote:
> On 05/17/2016 12:21 AM, Chen-Yu Tsai wrote:
>> Hi,
>>
>> On Tue, May 17, 2016 at 10:38 AM,  <tpearson at raptorengineering.com> wrote:
>>> ---
>>>  arch/arm/cpu/armv7/psci.S             | 1 +
>>>  arch/arm/cpu/armv7/sunxi/psci_sun6i.S | 4 ++--
>>>  arch/arm/cpu/armv7/sunxi/psci_sun7i.S | 4 ++--
>>>  3 files changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm/cpu/armv7/psci.S b/arch/arm/cpu/armv7/psci.S
>>> index 87c0c0b..18a0cc2 100644
>>> --- a/arch/arm/cpu/armv7/psci.S
>>> +++ b/arch/arm/cpu/armv7/psci.S
>>> @@ -203,6 +203,7 @@ ENTRY(psci_get_cpu_stack_top)
>>>         add     r5, r5, #0x2000                 @ Skip two pages
>>>         lsr     r5, r5, #12                     @ Align to start of page
>>
>> Why not just change this line instead?
>>
>> ChenYu
>>
>
> That would break page alignment, no?  The idea is to align the lower
> stack range address to a page (possibly wasting up to slightly less than
> a page in the process); changing this line would result in two pages
> wasted and the same amount of space available for the stack.

A page is 4 kiB, or 12 bits of address space. The alignment done above
is right shift 12 bits, followed by left shift 12 bits, which does not
matter if you add 0x2000 or 0x3000 to the address.

ChenYu

>
> --
> Timothy Pearson
> Raptor Engineering
> +1 (415) 727-8645 (direct line)
> +1 (512) 690-0200 (switchboard)
> https://www.raptorengineering.com