* Rick P. Edgecombe: > On Mon, 2022-10-10 at 12:56 +0200, Florian Weimer wrote: >> > + /* Only support enabling/disabling one feature at a time. */ >> > + if (hweight_long(features) > 1) >> > + return -EINVAL; >> >> This means we'll soon need three extra system calls for x86-64 >> process >> start: SHSTK, IBT, and switching off vsyscall emulation. (The latter >> does not need any special CPU support.) >> >> Maybe we can do something else instead to make the strace output a >> little bit cleaner? > > In previous versions it supported enabling multiple features in a > single syscall. Thomas Gleixner pointed out that (this was on the LAM > patchset that shared the interface at the time) it makes the behavior > of what to do when one feature fails to enable complicated: > > https://lore.kernel.org/lkml/87zgjjqico.ffs@tglx/ Can we return the bits for the features that were actually enabled? Those three don't have cross-dependencies in the sense that you would only use X & Y together, but not X or Y alone. Thanks, Florian
