On 25.01.2021 22:27, Stefano Stabellini wrote: > A recent thread [1] has exposed a couple of issues with our current way > of handling EXPERT. > > 1) It is not obvious that "Configure standard Xen features (expert > users)" is actually the famous EXPERT we keep talking about on xen-devel > > 2) It is not obvious when we need to enable EXPERT to get a specific > feature > > In particular if you want to enable ACPI support so that you can boot > Xen on an ACPI platform, you have to enable EXPERT first. But searching > through the kconfig menu it is really not clear (type '/' and "ACPI"): > nothing in the description tells you that you need to enable EXPERT to > get the option. > > So this patch makes things easier by doing two things: > > - introduce a new kconfig option UNSUPPORTED which is clearly to enable > UNSUPPORTED features as defined by SUPPORT.md > > - change EXPERT options to UNSUPPORTED where it makes sense: keep > depending on EXPERT for features made for experts > > - tag unsupported features by adding (UNSUPPORTED) to the one-line > description > > - clarify the EXPERT one-line description > > [1] https://marc.info/?l=xen-devel&m=160333101228981 > > Signed-off-by: Stefano Stabellini <stefano.stabell...@xilinx.com>
Non-Arm bits Reviewed-by: Jan Beulich <jbeul...@suse.com> However, I have questions on the Arm ones (sorry for not noticing earlier, as I assume it was this way before already): > @@ -77,7 +77,7 @@ config SBSA_VUART_CONSOLE > SBSA Generic UART implements a subset of ARM PL011 UART. > > config ARM_SSBD > - bool "Speculative Store Bypass Disable" if EXPERT > + bool "Speculative Store Bypass Disable (UNSUPPORTED)" if UNSUPPORTED > depends on HAS_ALTERNATIVE > default y > help > @@ -87,7 +87,7 @@ config ARM_SSBD > If unsure, say Y. > > config HARDEN_BRANCH_PREDICTOR > - bool "Harden the branch predictor against aliasing attacks" if EXPERT > + bool "Harden the branch predictor against aliasing attacks > (UNSUPPORTED)" if UNSUPPORTED > default y > help > Speculation attacks against some high-performance processors rely on Both of these default to y and have their _prompt_ conditional upon EXPERT. Which means only an expert can turn them _off_. Which doesn't make it look like these are unsupported? Or if anything, turning them off is unsupported? Jan
