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Date: Thu, 13 Apr 2017 10:37:05 +0000
From: Jaydeep Patil <Jaydeep.Patil@...tec.com>
To: Szabolcs Nagy <nsz@...t70.net>, "musl@...ts.openwall.com"
<musl@...ts.openwall.com>
CC: Andre McCurdy <armccurdy@...il.com>
Subject: RE: microMIPS32R2 O32 port
Hi Szabolcs,
Please find the attached patch.
Thanks,
Jaydeep
>-----Original Message-----
>From: Szabolcs Nagy [mailto:nsz@...t70.net]
>Sent: 13 April 2017 PM 02:31
>To: musl@...ts.openwall.com
>Cc: Andre McCurdy; Jaydeep Patil
>Subject: Re: [musl] [MUSL] microMIPS32R2 O32 port
>
>* Jaydeep Patil <Jaydeep.Patil@...tec.com> [2017-04-13 04:29:10 +0000]:
>> With this branch (micromips32r2_v2) we are supporting microMIPS cores
>that co-exist with MIPS. The MUSL library must be built with -minterlink-
>compressed option as there are couple of hand-written MIPS only functions.
>For microMIPS only cores we will create a different subarch.
>>
>
>ok the _v2 branch makes sense to me
>(the patch is sufficiently small that
>you can send it to the list)
>
>i think i was looking at _v1 before
>
>> >-----Original Message-----
>> >From: Andre McCurdy [mailto:armccurdy@...il.com]
>> >Sent: 13 April 2017 AM 03:17
>> >To: musl@...ts.openwall.com
>> >Cc: Jaydeep Patil
>> >Subject: Re: [musl] [MUSL] microMIPS32R2 O32 port
>> >
>> >On Wed, Apr 12, 2017 at 1:27 PM, Rich Felker <dalias@...c.org> wrote:
>> >> On Wed, Apr 12, 2017 at 09:25:35PM +0200, Szabolcs Nagy wrote:
>> >>> * Jaydeep Patil <Jaydeep.Patil@...tec.com> [2017-04-12 11:54:10
>+0000]:
>> >>> > Hi Rich,
>> >>> >
>> >>> > We can reuse existing MIPS code for microMIPS. There are places
>> >>> > where
>> >we read from $ra must be compiled for MIPS.
>> >>> > Please refer to https://github.com/JaydeepIMG/musl-
>> >1/tree/micromips32r2_v2 for modifications.
>> >>> >
>> >>>
>> >>> is micromips a different encoding for mips instructions that works
>> >>> on some cpus but not others?
>> >>
>> >> Yes, it's something like thumb or thumb2 on arm, or the riscv
>> >> compressed isa. What I'm not clear on is whether there are
>> >> micromips-only cpu models that can't execute normal mips.
>> >
>> >According to:
>> >
>> > https://imagination-technologies-cloudfront-
>>
>>assets.s3.amazonaws.com/documentation/MIPS_Architecture_microMIPS3
>2
>> >_InstructionSet_AFP_P_MD00582_06.04.pdf
>> >
>> >"microMIPS is also an alternative to the MIPS(r) instruction encoding
>> >and can be implemented in parallel or stand-alone."
>> >
>> >"If only one ISA mode exists (either MIPS or microMIPS) then this
>> >mode switch mechanism does not exist"
>> >
>> >> If so we probably need the ability to build musl as micromips, but
>> >> as long as cpus which support both support interworking (calls
>> >> between the two type of code in the same process) reasonably, I
>> >> don't think there's any reason to consider it a different subarch.
>> >>
>> >> If not (that is, if all cpus that support micromips also support
>> >> the normal mips isa) then I fail to see why there's any need to
>> >> compile musl's asm files as micromips. They're not size or
>> >> performance bottlenecks.
>> >>
>> >> Rich
Download attachment "microMIPS_32R2_v2.patch" of type "application/octet-stream" (1468 bytes)
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