Date: Wed, 12 Dec 2018 11:15:06 -0700 From: Warner Losh <imp@bsdimp.com> To: "freebsd-mips@freebsd.org" <freebsd-mips@freebsd.org> Subject: MIPS future... Message-ID: <CANCZdfpK5mPDDgpJ5PVhXF7-MixSouW8mAKkWQcaRnmYW%2Bpy0g@mail.gmail.com>
next in thread | raw e-mail | index | archive | help
OK. To be a good player in the FreeBSD ecosystem, we need to do a few things. First, we need to implement atomic_swap_64. hps did this for mips64 and committed it. He sent me some further patches for it that I need to commit when I get a change, maybe at the airport tonight. But this brings up a couple of issues I'd like to bring up. First, to implement atomic_swap_64 on mips-32 is hard. In that it's not just the canonical ldd/sdd sequence because those aren't available there. We can do the standard trick of reading STATUS0, clearing IE, storing it, do the operation and then restoring STATUS0. This is efficient enough for the use in the kernel for the supported cores we have. With two exceptions. First is running 32-bit kernels on 64-bit hardware. We deprecated that with Octeon because of the weird hacks we needed to do too make it work. I'd like to universally deprecate this. There's little benefit and a real cost to doing this. I'd like to remove the SWARM_SMP, XLP, and GXEMUL32 (or at least remove the smp option). But there's JZ4780. It's a legit mips32 + SMP. It's on Image Creator's CI20. This was released in Nov 2014 with a refresh in March 2015. This is a dead-end product line (there's no new cores and none new that I can find). This was a RPi competitor, but it was slower, less capable and more expensive so it's kinda rare now. I'd say we need to de-support this device. I know of only one user, and he's not responded to my email. I think 12 will have to be the last release we have this in. Today, the only affect is for some drivers that can't run on this platform, but the writing is on the wall. That brings me to my next question: SWARM. Can we kill SWARM entirely? It's for the BCM1250 part, released in sometime before 2000. It was super popular because it was the reference for a ton of things that followed. I think it's run is over and we can remove it. I can find no users of it in the nyc dmesg database. Mine has been in a plastic bag since before my sone was born in 2006... So I'm thinking we can remove this platform. It was on the edge last time I did a GC in mips-land. And then there's the even larger question: how many people are still using mips32? It looks like a fair number, maybe, but I have no idea for sure, so if you do, please provide feedback on the platforms you are running FreeBSD 11 or newer on. Warner
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CANCZdfpK5mPDDgpJ5PVhXF7-MixSouW8mAKkWQcaRnmYW%2Bpy0g>