On Wed, 14 Jul 2021 at 19:06, Richard Henderson <richard.hender...@linaro.org> wrote: > > Mirror the behavour of /proc/sys/abi/sve_default_vector_length > under the real linux kernel. We have no way of passing along > a real default across exec like the kernel can, but this is a > decent way of adjusting the startup vector length of a process. > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/482 > Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
> +#ifdef CONFIG_USER_ONLY > +/* Mirror linux /proc/sys/abi/sve_default_vector_length. */ /proc/sys/abi/sve_default_vector_length wants a vector length in bytes, and it looks like we take a length in bits. I assume that's to match other places where the user can specify vector lengths, but we should mention the units we expect and that it's not what the kernel uses. We also don't support the kernel's (undocumented) "-1 means set to the maximum" behaviour -- do we need it, or is that more reasonably achievable by the user via other properties ? Otherwise Reviewed-by: Peter Maydell <peter.mayd...@linaro.org> Regarding documentation, yeah, we don't have a great place to put usermode specific CPU properties. I would just put the documentation with the docs of the other properties. Maybe we'll sort out the document structure later (or at least put a link from the usermode doc section into the CPU part of the system-emulation doc section), but the usermode emulation documentation overall is in need of a massive overhaul some day... thanks -- PMM
