Messages in this thread | | | Date | Wed, 27 Mar 2024 09:14:47 +0800 | From | Jisheng Zhang <> | Subject | Re: [PATCH] riscv: deprecate CONFIG_MMU=n |
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On Tue, Mar 26, 2024 at 01:25:08PM -0700, Charles Lohr wrote: > Jisheng, are you using musl or uclibc? I've been having difficulty > getting new versions of each working with the newer kernels with > system calls not lining up.
Hi Charles,
I tested nommu linux with uclibc, both rv32 and rv64
Thanks
> > Also, is there a better place to ask questions about the more > user-spacy stuff? That's really where I've been struggling to > maintain things, keeping buildroot working when targeting RV32 NOMMU. > Thankfully a lot of the stickiest problems have all been upstreamed. > > Charles > > On Mon, Mar 25, 2024 at 10:12 AM Jisheng Zhang <jszhang@kernel.org> wrote: > > > > On Thu, Mar 14, 2024 at 09:02:43PM +0800, Jisheng Zhang wrote: > > > On Thu, Mar 14, 2024 at 08:46:21PM +0800, Jisheng Zhang wrote: > > > > On Tue, Feb 27, 2024 at 08:38:50AM -0800, Palmer Dabbelt wrote: > > > > > On Tue, 27 Feb 2024 01:11:41 PST (-0800), cleger@rivosinc.com wrote: > > > > > > > > > > > > > > > > > > On 26/02/2024 20:00, Charles Lohr wrote: > > > > > > > WOAH! Please DO NOT deprecate NOMMU. I use the NOMMU build constantly > > > > > > > and NOMMU Linux on RISC-V is the avenue used by many FPGA soft cores > > > > > > > for Linux, as well as some limited systems. > > > > > > > > > > OK. > > > > > > > > > > I just build test this stuff, as I don't really have a use for it > > > > > personally. I figured if nobody's reporting bugs then probably it's broken > > > > > and nobody's noticed because nobody's using it. > > > > > > > > > > > > I get new copies of the kernel when there are releases and test them > > > > > > > frequently to make sure everything is still working as expected. > > > > > > > > > > I'd actually expected it to be broken, but I guess we managed to avoid > > > > > screwing things up ;) > > > > > > > > > > > > For us we just don't care about XIP. I mean if someone did push it > > > > > > > > I don't care XIP either, and IMHO the XIP's maintenance effort is much > > > > bigger than NOMMU(just check the various XIP_FIXUP* or CONFIG_XIP_KERNEL > > > > macros around lowlevel pgtable.h, page.h). If we can remove XIP, the > > > > code readability will be much better. > > > > > > > > Or sending out a similar XIP deprecation patch to see whether there's > > > > any complain ? ;) > > > > > > > > > > > through to fruition, I'd also test and use it, but I urge you please > > > > > > > do not deprecate this. While it's sometimes needed a bit of a > > > > > > > > +1 for urge the upstream please do not deprecate NOMMU. > > > > > > > > Besides the soft(FPGA) core mentioned by Charles, here is another real > > > > > > And I'd like to write more about soft core: riscv is a free and open > > > ISA, this make it really good for education, for simple riscv > > > implementation or emulator. Once riscv IMA is implemented(even if MMU, > > > cache, TLB stuff don't exist), it's not far away from making linux > > > running on the FPGA or emulator. If the gain is larger than the maintenance > > > effort, I'd like to urge keeping the NOMMU support. > > > > > > Thanks a lot > > > > > > > usage case: As is known, Sophgo CV1800B platforms such as Milk Duo > > > > contains two C906 core, one(a.k.a big core) with MMU another(a.k.a small > > > > core)w/o MMU. The vendor sdk runs freertos on the small core, but it > > > > doesn't prevent users to run other OS such as threadx, zephyr or nommu > > > > linux on the small core. In fact, I sucessfully brought up nommu linux > > > > on the small core. I didn't just send out the patches in time during this > > > > dev window duo to my personal career reason(I spent the time on hunting > > > > for a new job) > > > > > > > > I plan to send out NOMMU related patches once 6.9-rc1 is out. > > > > As is promised, the NOMMU improvement patches are sent out > > https://lore.kernel.org/linux-riscv/20240325164021.3229-1-jszhang@kernel.org/T/#t > > > > Thanks > > > > > > > > > > > > > creative build to get everything working, I've never needed to patch > > > > > > > anything in the kernel beyond patching in a custom console for serial > > > > > > > output. > > > > > > > > > > > > > > > > > > > Hey Charles, > > > > > > > > > > > > No worries, we actually did not expected NOMMU to have *so many* users. > > > > > > I guess deprecating stuff is a good way to have immediate feedback ;). > > > > > > Having FDPIC psABI to be merged upstream could also probably be a > > > > > > positive point toward a better NOMMU support. > > > > > > > > > > Ya, that's probably the right way to do it. Touching anything in the psABI > > > > > is pretty miserable, though, so I don't really want to force people to do > > > > > it... > > > > > > > > > > > > I am happy to discuss the possibility of me and or one of the other > > > > > > > RISC-V soft (FPGA) core people stepping up to try to be more active, > > > > > > > but so far we've just been very well serviced by the current NOMMU > > > > > > > Linux setup. > > > > > > > > > > > > It could probably be nice to have some feedback/Tested-by: from NOMMU > > > > > > users for new releases then. > > > > > > > > > > Having more upstream interaction from users is always appreciated, that's > > > > > the best way to prove people are using the code. If you guys have the time > > > > > it'd be great to get this into some sort of CI, ideally running on some real > > > > > platform. > > > > > > > > As above, I'd also like to step up on the NOMMU stuff, at least test > > > > nommu on milkv duo's small core. And can be seen from my git commit > > > > histotry, I was active, and I belive I will still be active on riscv linux > > > > kernel development. > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > Clément > > > > > > > > > > > > > > > > > > > > Charles > > > > > > > > > > > > > > > > > > > > > On Mon, Feb 26, 2024 at 8:03 AM Conor Dooley <conor@kernel.org> wrote: > > > > > > > > > > > > > > > > On Mon, Feb 26, 2024 at 04:25:24PM +0100, Clément Léger wrote: > > > > > > > > > I guess I could also mark XIP as deprecated. > > > > > > > > > > > > > > > > I'm not so sure, people recently added XIP support to QEMU (and sent > > > > > > > > kernel fixes in December). XIP is also not nearly as much of a problem > > > > > > > > to support, there's far less that it does differently, the main barrier > > > > > > > > was the inability to test it which is no longer the case. > > > > > > > > That said, XIP is gonna kill itself off I feel as it does not support > > > > > > > > runtime patching and therefore is extremely limited on extensions, given > > > > > > > > we use alternatives for all of that (although I suppose if someone has a > > > > > > > > usecase they could make nasty macros worse and implement a compiletime > > > > > > > > switch in the alternatives too). > > > > > > > > > > > > > > > > Cheers, > > > > > > > > Conor. > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > linux-riscv mailing list > > > > > > > > linux-riscv@lists.infradead.org > > > > > > > > http://lists.infradead.org/mailman/listinfo/linux-riscv > > > > > > > > > > _______________________________________________ > > > > > linux-riscv mailing list > > > > > linux-riscv@lists.infradead.org > > > > > http://lists.infradead.org/mailman/listinfo/linux-riscv
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