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

2016-05-17 Thread Chen-Yu Tsai 
On Wed, May 18, 2016 at 3:19 AM, Timothy Pearson
 wrote:
> On 05/17/2016 12:21 AM, Chen-Yu Tsai wrote:
>> Hi,
>>
>> On Tue, May 17, 2016 at 10:38 AM,   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
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Re: [U-Boot] [PATCH 3/8] sun8i: Extend stack size to allow for up to 8 CPUs

2016-05-17 Thread Timothy Pearson 
On 05/17/2016 12:21 AM, Chen-Yu Tsai wrote:
> Hi,
> 
> On Tue, May 17, 2016 at 10:38 AM,   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.

-- 
Timothy Pearson
Raptor Engineering
+1 (415) 727-8645 (direct line)
+1 (512) 690-0200 (switchboard)
https://www.raptorengineering.com
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Re: [U-Boot] [PATCH 3/8] sun8i: Extend stack size to allow for up to 8 CPUs

2016-05-16 Thread Chen-Yu Tsai 
Hi,

On Tue, May 17, 2016 at 10:38 AM,   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

> lsl r5, r5, #12
> +   add r5, r5, #0x1000 @ Skip an additional page
> sub r5, r5, #4  @ reserve 1 word for target PC
> sub r0, r5, r0  @ here's our stack!
>
> diff --git a/arch/arm/cpu/armv7/sunxi/psci_sun6i.S 
> b/arch/arm/cpu/armv7/sunxi/psci_sun6i.S
> index 90b5bfd..d35b63e 100644
> --- a/arch/arm/cpu/armv7/sunxi/psci_sun6i.S
> +++ b/arch/arm/cpu/armv7/sunxi/psci_sun6i.S
> @@ -32,8 +32,8 @@
>   * ._secure_text section
>   * text_end to ALIGN_PAGE(text_end):
>   * nothing
> - * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x1000)
> - * 1kB of stack per CPU (4 CPUs max).
> + * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x2000)
> + * 1kB of stack per CPU (8 CPUs max).
>   */
>
> .pushsection ._secure.text, "ax"
> diff --git a/arch/arm/cpu/armv7/sunxi/psci_sun7i.S 
> b/arch/arm/cpu/armv7/sunxi/psci_sun7i.S
> index e15d587..b8ac50e 100644
> --- a/arch/arm/cpu/armv7/sunxi/psci_sun7i.S
> +++ b/arch/arm/cpu/armv7/sunxi/psci_sun7i.S
> @@ -32,8 +32,8 @@
>   * ._secure_text section
>   * text_end to ALIGN_PAGE(text_end):
>   * nothing
> - * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x1000)
> - * 1kB of stack per CPU (4 CPUs max).
> + * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x2000)
> + * 1kB of stack per CPU (8 CPUs max).
>   */
>
> .pushsection ._secure.text, "ax"
> --
> 2.8.0.rc3
>
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[U-Boot] [PATCH 3/8] sun8i: Extend stack size to allow for up to 8 CPUs

2016-05-16 Thread tpearson 
---
 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
lsl r5, r5, #12
+   add r5, r5, #0x1000 @ Skip an additional page
sub r5, r5, #4  @ reserve 1 word for target PC
sub r0, r5, r0  @ here's our stack!

diff --git a/arch/arm/cpu/armv7/sunxi/psci_sun6i.S 
b/arch/arm/cpu/armv7/sunxi/psci_sun6i.S
index 90b5bfd..d35b63e 100644
--- a/arch/arm/cpu/armv7/sunxi/psci_sun6i.S
+++ b/arch/arm/cpu/armv7/sunxi/psci_sun6i.S
@@ -32,8 +32,8 @@
  * ._secure_text section
  * text_end to ALIGN_PAGE(text_end):
  * nothing
- * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x1000)
- * 1kB of stack per CPU (4 CPUs max).
+ * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x2000)
+ * 1kB of stack per CPU (8 CPUs max).
  */

.pushsection ._secure.text, "ax"
diff --git a/arch/arm/cpu/armv7/sunxi/psci_sun7i.S 
b/arch/arm/cpu/armv7/sunxi/psci_sun7i.S
index e15d587..b8ac50e 100644
--- a/arch/arm/cpu/armv7/sunxi/psci_sun7i.S
+++ b/arch/arm/cpu/armv7/sunxi/psci_sun7i.S
@@ -32,8 +32,8 @@
  * ._secure_text section
  * text_end to ALIGN_PAGE(text_end):
  * nothing
- * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x1000)
- * 1kB of stack per CPU (4 CPUs max).
+ * ALIGN_PAGE(text_end) to ALIGN_PAGE(text_end) + 0x2000)
+ * 1kB of stack per CPU (8 CPUs max).
  */

.pushsection ._secure.text, "ax"
-- 
2.8.0.rc3

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