It is a Chinese MIPS-based Arch [LWN.net]

It is a Chinese MIPS-based Arch

Posted Dec 23, 2025 12:00 UTC (Tue) by ballombe (subscriber, #9523)
In reply to: It is a Chinese MIPS-based Arch by gmatht
Parent article: Loong64 is now an official Debian architecture

Yes it is very similar to mips r6, except for some reason they use different asm syntax for operand.
(eg daddu became add.d) so one have to modify existing mips64 asm code.
Probably the motivation is that mips r6 was abandoned in favor of risc-v but China has invested too much on mips64 (instead of arm) to switch.

Debian has a long history of supporting MIPS (mips, mipsel, mipsel64) so why not.

It is a Chinese MIPS-based Arch

Posted Dec 24, 2025 6:49 UTC (Wed) by mirabilos (subscriber, #84359) [Link]

Debian just threw out all MIPS support, though :(

It is a Chinese MIPS-based Arch

Posted Dec 26, 2025 11:58 UTC (Fri) by justincormack (subscriber, #70439) [Link]

re "China has invested too much on mips64 (instead of arm) to switch" - this doesn't seem uniform across different Chinese companies, and loong still seems fairly niche there as far as I can make out from talking to people. Huawei are still all in on Arm, although they no longer have access to more recent Arm versions so they are continuing to develop the ones they had licenses for. Risc-V is also being developed elsewhere.

It is a Chinese MIPS-based Arch

Posted Jan 2, 2026 12:33 UTC (Fri) by anton (subscriber, #25547) [Link]

Originally Loongson started with MIPS, but Loongarch is a different, although similar instruction set (just as Alpha and RISC-V also have similarities with MIPS). Not just the mnemonics are different, but also the encodings (otherwise one could just reactivate the Debian MIPS port for Loongarch. E.g., Loongarch "add.d r1, r1, r1" encodes to 0x108421, while MIPS "daddu r1, r1, r1" encodes to 0x21082D.

One interesting aspect is that many instruction sets with 32-bit and 64-bit variants define the regular add from the 32-bit architecture to work on 64-bit values in the 64-bit variant (e.g., SPARC, Power, RISC-V). Some (RISC-V) define a 32-bit variant that sign- or zero-extends the low 32 bits of the result. MIPS instead defines the regular addu from MIPS-I (32-bit) as the sign-extending variant and defines a 64-bit daddu in MIPS64; Loongarch apparently follows MIPS in that decision.

Concerning "Chinese architectures", as another poster wrote, there is quite a bit of diversity in the architectures used by Chinese companies, including those that are considered to be close to the government by the USA.