On Wed, 7 Aug 2019, Palmer Dabbelt wrote: > The ISA strings we're providing from QEMU aren't actually legal RISC-V > ISA strings, as both the S and U extensions cannot exist as > single-letter extensions and must instead be multi-letter strings. > We're still using the ISA strings inside QEMU to track the availiable > extensions, so this patch just strips out the S and U extensions when > formatting ISA strings. > > This boots Linux on top of 4.1-rc3, which no longer has the U extension > in /proc/cpuinfo. > > Signed-off-by: Palmer Dabbelt <pal...@sifive.com> > --- > This is another late one, but I'd like to target it for 4.1 as we're > providing illegal ISA strings and I don't want to bake that into a bunch > of other code.
I'm unfamiliar with the underlying QEMU code beyond the patch posted here, but I can review the intention expressed in the patch description. The described intent is aligned with Section 22.6 and Table 22.1 of the RISC-V User-Level ISA Specification version 2.2: https://github.com/riscv/riscv-isa-manual/blob/master/release/riscv-spec-v2.2.pdf And on the Linux kernel side we've also recognized that our current parsing code is handling "s" and "u" incorrectly and that we'll need to fix it: https://lore.kernel.org/linux-riscv/alpine.deb.2.21.9999.1908061818360.13...@viisi.sifive.com/ - Paul
