[Buildroot] [PATCH] micropython: Set MPZ_DIG_SIZE=32 for 64 bit targets

[Chris Packham]

Hi Vincent,

On Fri, Sep 18, 2015 at 10:02 PM, Vicente Olivert Riera
<Vincent.Riera at imgtec.com> wrote:
> Dear Chris Packham,
>
> On 09/18/2015 10:51 AM, Chris Packham wrote:
>> From the micropython source:
>>
>>   This mpz module implements arbitrary precision integers.
>>
>>   The storage for each digit is defined by mpz_dig_t.  The actual number
>>   of bits in mpz_dig_t that are used is defined by MPZ_DIG_SIZE.  The
>>   machine must also provide a type that is twice as wide as mpz_dig_t,
>>   in both signed and unsigned versions
>>
>>   MPZ_DIG_SIZE can be between 4 and 8*sizeof(mpz_dig_t), but it makes
>>   most sense to have it as large as possible.
>>
>> Micropython detects x86_64 targets and sets MPZ_DIG_SIZE appropriately
>> but for other 64-bit targets we need to explicitly pass
>> -DMPZ_DIG_SIZE=32 in CFLAGS.
>>
>> Signed-off-by: Chris Packham <judge.packham at gmail.com>
>> ---
>>  package/micropython/micropython.mk | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/package/micropython/micropython.mk b/package/micropython/micropython.mk
>> index 6266882..1ac2e8d 100644
>> --- a/package/micropython/micropython.mk
>> +++ b/package/micropython/micropython.mk
>> @@ -16,6 +16,10 @@ ifeq ($(BR2_powerpc)$(BR2_sh)$(BR2_xtensa),y)
>>  MICROPYTHON_CFLAGS = -DMICROPY_GCREGS_SETJMP=1
>>  endif
>>
>> +ifeq ($(BR2_ARCH_IS_64),y)
>> +MICROPYTHON_CFLAGS += -DMPZ_DIG_SIZE=32
>> +endif
>> +
>
> you have to take into account that MIPS64 n32 is a 64-bit target as
> well, but it has a MP_SSIZE_MAX of 32-bit. So, if you set MPZ_DIG_SIZE
> to 32 for all 64-bit arches, then you will see the same failure for the
> when building for MIPS64 n32.
>
> I suggest you to do modify the "ifeq" like this:
>
> # MIPS64 n32 is a 64-bit arch, but it has a 32-bit wide SSIZE_MAX which
> # means we still need the default MPZ_DIG_SIZE of 16.
> ifeq ($(BR2_ARCH_IS_64)$(BR2_MIPS_NABI32),y)
>

I'll take a look. The remote machine I was doing my buildroot hacking
on has gone AWOL so it may take a while for me to get it back up and
running (there was a planned server outage so I suspect it's trying to
access some non-existent mounts).

When I asked upstream there was a thought that this commit[1] might
fix the issue. So I'll try adding that as a patch first.

--
[1] - https://github.com/micropython/micropython/commit/8b4fb4fe140e9cf57fcfa258d0d2d6fe19090fc5