On Fri, Aug 6, 2021 at 11:54 PM Bin Meng <[email protected]> wrote: > > On Fri, Aug 6, 2021 at 8:58 PM Jessica Clarke <[email protected]> wrote: > > > > > On Fri, Aug 6, 2021 at 10:39 AM Bin Meng <[email protected]> wrote: > > > > > > > > On Fri, Aug 6, 2021 at 1:57 AM Ruinland Chuan-Tzu Tsai > > > > <[email protected]> wrote: > > > > > > > > > > From: Ruinland ChuanTzu Tsai <[email protected]> > > > > > > > > > > Adding option `riscv_custom` to configure script, meson.build and > > > > > meson_options.txt so as to toggle custom CSR and will-be-upstreamed > > > > > custom > > > > > instructions handling logic. > > > > > > > > > > Signed-off-by: Dylan Jhong <[email protected]> > > > > > --- > > > > > configure | 6 ++++++ > > > > > meson.build | 2 ++ > > > > > meson_options.txt | 2 ++ > > > > > 3 files changed, 10 insertions(+) > > > > > > > > > > > > > This sounds like unnecessary to bring such a config option to the meson > > > > level. > > > > > > > > I believe a Kconfig option should just be fine. > > > > > > +Alistair > > > > I don’t see why this is even a config option. If you request a vendor’s > > CPU you should get any custom CSRs defined for that vendor’s CPU. If > > you don’t you don’t. This should be purely a run-time thing, no? > > In a generic use case where we build all RISC-V machines into one > qemu-system-riscv{32,64} executable this makes no difference. The > Kconfig option will be turned on if any one of the machines requires > it. It only gets benefits when we build a QEMU executable on a > per-machine basis.
I agree with Bin that this could be a Kconfig option, that is selected when a vendor CPU is enabled. It also doesn't have to be a config and could just be built all the time. I don't see much of an advantage in allowing it to be disabled, it's just another thing we would need to test. Maybe is a user was just interested in the virt machine/KVM they could disable it to avoid any overhead. Alistair > > Regards, > Bin >
