RISC-V/HiFive memory limitations

[Denis Obrezkov]

2017-06-20 4:00 GMT+03:00 Joel Sherrill <joel at rtems.org>:

>
>
> On Jun 19, 2017 5:37 PM, "Denis Obrezkov" <denisobrezkov at gmail.com> wrote:
>
> 2017-06-20 1:23 GMT+03:00 Hesham Almatary <heshamelmatary at gmail.com>:
>
>>
>>
>> On Tue, Jun 20, 2017 at 7:33 AM, Denis Obrezkov <denisobrezkov at gmail.com>
>> wrote:
>>
>>> 2017-06-20 0:19 GMT+03:00 Joel Sherrill <joel at rtems.org>:
>>>
>>>> Check the value in gdb without loading it on a target.
>>>>
>>>> Gdb hello.exe
>>>>
>>>> p symbol
>>>>
>>>
>>>> Since it is a constant, it should be as expected. If it is, you have a
>>>> code loading issue.
>>>>
>>> Yes, it is 512 in gdb, as expected. So, is the problem with linkcmd
>>> file?
>>>
>>>>
>>>> Is that value by any chance an instruction?
>>>>
>>> No don't think so.
>>
>>
>>> How to check whether it is an instruction or not?
>>>
>>> You can check if this value might match with any riscv32 instruction
>> encodings (I believe it doesn't). See Chapter 19 (RV32/64G Instruction Set
>> Listings) user-level riscv-spec 2.3-draft. You can also use
>> riscv32-rtems4.12-objdump on your binary and search for this value.
>>
>> I was also able to run gdb, connect to the target,  change the value of
>>> the variable to 512,
>>> reconnect to the target, make loading and read the value equal to 512.
>>>
>>>
>>>
>>> --
>>> Regards, Denis Obrezkov
>>>
>>
>>
>>
>> --
>> Hesham
>>
>
> I didn't find this value in objdump
> I think that .data section wasn't properly initialized, does it look
> reasonable?
>
>
> I suspect it means that the image is not properly loaded into memory.
> Download but don't execute. Then check the address.
>
> If it correct on download, then binary search with breakpoints and
> checking​ the memory. Or set a hardware watchpoint on a write to that
> address.
>
> Hesham.. does the crt code have to copy a secondary copy of the .data
> initial values into place on this bsp?
>
>
>
> --
> Regards, Denis Obrezkov
>
>
> The wrong value is present right after loading, before the execution.

-- 
Regards, Denis Obrezkov
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