On 01.04.2022 22:00:35, Palmer Dabbelt wrote: > As pointed out recently [1], sparse is parsing -march on RISC-V in order > to obtain the default set of preprocessor macros to use. Back when this > was written ISA string was a simple affair, but these days it's a lot > more complicated. It's going to be a big chunk of work to get a proper > ISA string parser into sparse, but we can at least fix the breakages for > the subset of legal ISA strings that Linux currently uses (and are > breaking users). > > This patch set does three things: > > * Stops die()ing on unknown ISA strings, unless the user has passed > -Wsparse-error. This prints a warning and guesses at the macros to > use, which is probably fine for Linux. > * Cleans up some of the differences between GCC's -march parsing and > sparse's. None of this should really matter for Linux, as GCC will > blow up on bad ISA strings, but it just seemed worth doing when I was > in there. > * Adds support for the Zicsr and Zifencei extensions, which were > recently enabled. With these the unknown ISA string warning goes away > for Linux builds. > > They're all sort of independent (and happen in this order), but they're > all touching the same code so I'm just sending it as a series. It's my > first time touching sparse. > > I've poked around with the first patch on its own and it seems to > largely work as expected: I'm still getting a bunch of sparse-related > warnings when I turn on sparse in my builds, but at least I don't get an > error (after updating to a binutils that supports the new arguments, so > Linux detects them). I tried CF="-Wsparse-error", which also behaves as > expected (that trinary boolean tripped me up for a bit). > > The first patch alone should be a sufficient band-aid for systems that > are actively broken right now, the rest are cleanups -- these may be > necessary to get the RISC-V port sparse-clean, but that's a WIP so there > might be more. I'm going to play around with that, but just looking at > the volume of spew it's probably going to take a while. I gave these > patches a bit of testing one-by-one, but not nearly as much as the > first. > > I just spun up a sparse repo [2] at kernel.org, these are on the riscv > branch if that helps for anyone. I've also started messing around with > parsing a few more of the multi-letter extensions, but there's so much > coupling I got fed up -- it's on riscv-wip, but I definitely don't like > that last patch. I figured it's better to send out these bits, as they > look solid to me and builds are broken. The new stuff (B, K, and V) are > all in GCC-12 anyway, so we have a bit of time before they're useful. > > [1]: https://lore.kernel.org/linux-sparse/mhng-c280d48c-477d-4589-baee-255c774b5a51@palmer-mbp2014/T/#maef705f448e4a1f12d853c0d8bc756f037ce1ce0 > [2]: https://git.kernel.org/pub/scm/linux/kernel/git/palmer/sparse.git Works without warnings on Debian testing, with gcc-riscv64-linux-gnu 4:11.2.0--1. Tested-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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