[PATCH 2/2] bsps/arm: Sort fast text/data sections

[Chris Johns]

On 21/10/20 4:51 pm, Sebastian Huber wrote:
> On 21/10/2020 07:42, Chris Johns wrote:
> 
>> On 21/10/20 4:31 pm, Sebastian Huber wrote:
>>> On 21/10/2020 02:25, Chris Johns wrote:
>>>
>>>> On 21/10/20 3:04 am, Sebastian Huber wrote:
>>>>> ---
>>>>>    bsps/arm/shared/start/linkcmds.base | 4 ++--
>>>>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/bsps/arm/shared/start/linkcmds.base
>>>>> b/bsps/arm/shared/start/linkcmds.base
>>>>> index d0663cf97e..8fa127ce08 100644
>>>>> --- a/bsps/arm/shared/start/linkcmds.base
>>>>> +++ b/bsps/arm/shared/start/linkcmds.base
>>>>> @@ -290,7 +290,7 @@ SECTIONS {
>>>>>          .fast_text : ALIGN_WITH_INPUT {
>>>>>            bsp_section_fast_text_begin = .;
>>>> What is `fast text` (and fast data)? I have not heard of this before and I
>>>> cannot find anything on it?
>>> I added this section 11 years ago as a section for code which could reside in a
>>> faster memory. For example, normal code could reside on a 16-bit SDRAM and the
>>> fast code on an internal 32-bit SRAM in a chip without a cache. In the recent
>>> Cortex-M7 BSPs, the fast text is mapped to the ITCM.
>> OK. Is anything written up about this?
> No, maybe we should add something about this in the arm BSP section of the user
> manual.

That would be helpful.

>> For example is allocating variables
>> automatic or can I control allocation to it?
> 
> You just have to place a function or variable with the section attribute into
> these sections:
> 
> bsps/arm/include/bsp/linker-symbols.h:#define BSP_FAST_TEXT_SECTION \
> bsps/arm/include/bsp/linker-symbols.h- RTEMS_SECTION(".bsp_fast_text")
> 
> bsps/arm/include/bsp/linker-symbols.h:#define BSP_FAST_DATA_SECTION \
> bsps/arm/include/bsp/linker-symbols.h- RTEMS_SECTION(".bsp_fast_data")

I think would be good to document otherwise no one will know it exists or how it
can be used.

Chris