On Mon, Aug 04, 2025 at 01:44:21PM +0900, Simon Richter wrote: > Hi, > > On 8/4/25 05:44, Eric Biggers wrote: > > > Taken together, it's clear that it's time to retire these additional MD5 > > implementations, and focus maintenance on the MD5 generic C code. > > [...] > > > - ldd [%o1 + 0x00], %f8 > > - ldd [%o1 + 0x08], %f10 > > - ldd [%o1 + 0x10], %f12 > > - ldd [%o1 + 0x18], %f14 > > - ldd [%o1 + 0x20], %f16 > > - ldd [%o1 + 0x28], %f18 > > - ldd [%o1 + 0x30], %f20 > > - ldd [%o1 + 0x38], %f22 > > - > > - MD5 > > This is a literal CPU instruction that ingests sixteen registers (f8 to f23) > and updates the hash state in f0 to f3.
Note that QEMU doesn't support this instruction. I don't actually know whether the SPARC64 MD5 code even works, especially after (presumably untested) refactoring like commit cc1f5bbe428c91. I don't think anyone does, TBH. No one seems to be running the crypto tests on SPARC64. > I can see the point of removing hand-optimized assembler code when a > compiler can generate something that runs just as well from generic code, > but this here is using CPU extensions that were made for this specific > purpose. You do realize this is MD5, right? And also SPARC64? I'm confused why people are so attached to still having MD5 assembly code in 2025, and *only for rare platforms*. It's illogical. We should just treat MD5 like the other legacy algorithms MD4 and RC4, for which the kernel just has generic C code. That works perfectly fine for the few users that still need those algorithms for compatibility reasons. > This is exactly the kind of thing you would point to as an argument why > asynchronous hardware offload support is unnecessary. For an algorithm that is actually worthwhile to accelerate, sure. For MD5, it's not worthwhile anyway. - Eric
