Bug#825024: linux: add MIPS r6 and N32 support

[YunQiang Su <wzssyqa@gmail.com>]

On Mon, May 23, 2016 at 2:30 AM, Ben Hutchings <ben@decadent.org.uk> wrote:
> Control: tag -1 moreinfo
>
> On Sun, 2016-05-22 at 22:52 +0800, YunQiang Su wrote:
>> Package: src:linux
>> Version: 4.5 - 4.6
>>
>> Hi, this patch add mipsn32 and mipsn32el support and also add
>> 6 MIPS r6 architectures.
>>
>> mipsn32 and mipsn32el have same flavors with mips64 and mips64el.
>
> Since we have multiarch it is not necessary to duplicate kernel
> packages with identical configurations in multiple Debian
> architectures.  All the N32 architectures should be used in multiarch
> configurations together with the corresponding 64-bit architectures.
> (The same should be true for O32 architectures, but that won't happen
> until the corresponding 64-bit architectures are in the main archive.)

I won't push N32 architecture to the main Debian archive.
I just wish the code in the upstream, so I will not have to maintain another
git repo, and merge patches again and again.

In fact, I may build a standalone N32 private archive in future.

>
> [...]
>> --- a/debian/config/defines
>> +++ b/debian/config/defines
>> @@ -13,8 +13,16 @@ arches:
>>   m68k
>>   mips
>>   mipsel
>> + mipsn32
>> + mipsn32el
>>   mips64
>>   mips64el
>> + mipsr6
>> + mipsr6el
>> + mipsn32r6
>> + mipsn32r6el
>> + mips64r6
>> + mips64r6el
> [...]
>
> This is ridiculous.  12 different Debian architectures for MIPS?!  If
> you want to make ARM look like a better choice, this sort of
> fragmentation of binary compatibility is a good way to do it.
>
> Why are there new Debian architectures specifically for R6, given that
> Debian architectures correspond to ABIs and not specific CPU
> requirements (e.g.. i386's CPU requirements have graudally moved up
> from 386 to 686-class)?

Please see the talk on
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=807340

MIPS R6 is a new release of MIPS32 and MIPS64.
R6 is not fully compatible with R5-,
as it adds and *removes* some instructions, and add emulation
of the removed instructions in kernel,
so old binaries can still run on new R6 CPUs.

While for the new CPUs, we still wish they can have their own architectures.

In future, we may add them to the official Debian archive,
while now, it is just a prepare.




>
> Ben.
>
> --
> Ben Hutchings
> friends: People who know you well, but like you anyway.



-- 
YunQiang Su