[meta-xilinx] [PATCH] arm-trusted-firmware: Use constants for memory addresses

[Mike Looijmans]

On 29-09-16 16:22, Nathan Rossi wrote:
> On Thu, Sep 29, 2016 at 7:46 PM, Mike Looijmans <mike.looijmans at topic.nl> wrote:
>> On 28-09-16 17:20, Nathan Rossi wrote:
>>>
>>> On Wed, Sep 28, 2016 at 10:50 AM, Manjukumar Harthikote Matha
>>> <manjukumar.harthikote-matha at xilinx.com> wrote:
>>>>
>>>> Hi Mike,
>>>>
>>>> <.....>
>>>>>>>
>>>>>>>    LD[unexport] = "1"
>>>>>>>
>>>>>>> +ZYNQMP_ATF_MEM_BASE = "0xfffe5000"
>>>>>>> +ZYNQMP_ATF_MEM_SIZE =    "0x16000"
>>>>>>
>>>>>> Maybe reading the load address from elf might help. I think MEM_BASE
>>>>>> address might change going forward.
>>>>>>
>>>>>> For example:
>>>>>> https://github.com/Xilinx/arm-trusted-firmware/commit/eb4fa652d424b895
>>>>>> 7a927c6137e2ae3652b0b1bb
>>>>>>
>>>>>
>>>>> This patch was to accommodate that. The current version will load it at
>>>>> the wrong
>>>>> location.
>>>>>
>>>> I am looking to see if we can read from the generated elf and populate
>>>> the MEM_BASE and MEM_SIZE
>>>> With the current patch, I think it will be maintenance burden every
>>>> release, trying to mitigate it if possible.
>>>
>>>
>>> The generated bl31.elf is populated with the correct entry point address:
>>>     Entry point address:               0xfffe5000
>>>
>>> Which is pointing to bl31_entrypoint,
>>>
>>> https://github.com/Xilinx/arm-trusted-firmware/blob/eb4fa652d424b8957a927c6137e2ae3652b0b1bb/bl31/bl31.ld.S#L35
>>>
>>> Which could be used as an alternate source of the address:
>>>      625: 00000000fffe5000   212 FUNC    GLOBAL DEFAULT    1
>>> bl31_entrypoint
>>>
>>> My only query is whether the ZYNQ_ATF_MEM_* variables make sense as
>>> overrides? Essentially if there is a potential use case when bl31
>>> needs to be built to execute in an older/newer environment that
>>> differs from the default values (of the current version used)?
>>>
>>
>> What I really wanted is the opposite, get the address from the binary. That
>> would solve the "magic number" that you have to put in the recipe. I
>> couldn't find a way to do that, so I did the opposite, make sure that both
>> code and recipe share the same magic number.
>>
>> I had no intention of making this "configurable" or so, I just wanted it
>> consistent.
>>
>>
>
> That makes it simpler then :). I have a sent a patch that does the
> dynamic reading from the elf to solve this. If you could please give
> it a test and let me know that it works as you expect.

Looks fine, and a lot better than what I came up with. Probably won't be able 
to test today though.

M.



Kind regards,

Mike Looijmans
System Expert

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