[U-Boot] [PATCH v3 01/11] armv8: Add global variable resv_ram

[york sun]

On 03/12/2017 01:21 PM, Simon Glass wrote:
> Hi York,
>
> On 3 March 2017 at 09:38, york sun <york.sun at nxp.com> wrote:
>>
>> On 03/02/2017 08:53 PM, Simon Glass wrote:
>>> Hi York,
>>>
>>> On 1 March 2017 at 12:32, York Sun <york.sun at nxp.com> wrote:
>>>> Use gd->arch.resv_ram to track reserved memory allocation.
>>>>
>>>> Signed-off-by: York Sun <york.sun at nxp.com>
>>>> ---
>>>>
>>>> Changes in v3: None
>>>> Changes in v2: None
>>>>
>>>>  arch/arm/cpu/armv8/fsl-layerscape/Kconfig | 6 ++++++
>>>>  arch/arm/include/asm/global_data.h        | 3 +++
>>>>  cmd/bdinfo.c                              | 4 ++++
>>>>  3 files changed, 13 insertions(+)
>>>>
>>>> diff --git a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
>>>> index adccdf1..a40556f 100644
>>>> --- a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
>>>> +++ b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
>>>> @@ -273,6 +273,12 @@ config SYS_FSL_SDHC_CLK_DIV
>>>>           clock, in another word SDHC_clk = Platform_clk / this_divider.
>>>>  endmenu
>>>>
>>>> +config RESV_RAM_TOP
>>>> +       bool
>>>> +       help
>>>> +         Reserve memory from the top, tracked by gd->arch.resv_ram. It's up
>>>> +         to implementation to allow access to this reserved memory or not.
>>>
>>> This is not sufficiently descriptive IMO. What is it used for? What do
>>> you mean by 'from the top'? What is the top?
>>
>> Simon,
>>
>> How about renaming it to RESV_RAM?
>>
>> config RESV_RAM
>>          bool
>>         help
>>           Reserve memory from the RAM, tracked by gd->arch.resv_ram.
>>            This reserved RAM can be used by special driver that resides
>>            in memory after U-Boot exits. It's up to the implementation
>>            to allocate and allow access to this reserved memory. For
>>            example, the reserved RAM can be at the high end of physical
>>            memory. The reserved RAM may be excluded from the memory
>>            bank(s) passed to OS, or marked as reserved.
>
> OK, or perhaps RESERVED_RAM.
>
> In the description you say 'can be' and 'may me'. What determines
> whether it is or not?

I think our emails crossed each other. I see you have reviewed the v5 
patch. To answer your questions, it is up to individual implement how to 
use the reserved RAM. I used an example to put it at the high end of 
memory. It can also be put at the low end of high region memory. This 
part of memory can be carved out from the memory bank information passed 
to OS, or marked as reserved. It is also implementation-dependent 
because how the reserved RAM is used is up to each platform.

York