[rtems commit] bsp/riscv: Initialize FPU depending on ISA

[Sebastian Huber]

On 01/08/18 12:06, Hesham Almatary wrote:
> On Wed, Aug 1, 2018 at 10:18 AM, Sebastian Huber <sebh at rtems.org> wrote:
>> Module:    rtems
>> Branch:    master
>> Commit:    529154bad207a42a6d0f03343c7e215eab97ced5
>> Changeset: http://git.rtems.org/rtems/commit/?id=529154bad207a42a6d0f03343c7e215eab97ced5
>>
>> Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
>> Date:      Tue Jul 31 09:15:00 2018 +0200
>>
>> bsp/riscv: Initialize FPU depending on ISA
>>
>> Initialize fcsr to zero for a defined rounding mode.
>>
>> Update #3433.
>>
>> ---
>>
>>   bsps/riscv/riscv/start/start.S | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/bsps/riscv/riscv/start/start.S b/bsps/riscv/riscv/start/start.S
>> index 290c95a..feb07fe 100644
>> --- a/bsps/riscv/riscv/start/start.S
>> +++ b/bsps/riscv/riscv/start/start.S
>> @@ -48,9 +48,12 @@ SYM(_start):
>>          LADDR   gp, __global_pointer$
>>          .option pop
>>
>> -       /* Init FPU unit if it's there */
>> +       /* Init FPU */
>> +#ifdef __riscv_flen
>>          li      t0, MSTATUS_FS
>>          csrs    mstatus, t0
>> +       csrw    fcsr, zero
>> +#endif
> Do you think it makes sense to check the MISA register for checking
> the existence of an FPU unit or not?

I considered adding run-time tests here. I decided to not do it since we 
should offer a good multilib for a particular chip. It is the duty of 
the user to select the right multilib for its chip.

-- 
Sebastian Huber, embedded brains GmbH

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