On 05/03/2025 at 23:30, Andy Shevchenko wrote: > On Wed, Mar 05, 2025 at 10:00:15PM +0900, Vincent Mailhol via B4 Relay wrote: >> From: Yury Norov <yury.norov@xxxxxxxxx> >> >> Add __GENMASK_t() which generalizes __GENMASK() to support different > > Is it with double underscore? I do not see it. This is my mistake. In an earlier draft, it was __GENMASK_t(), meanwhile, I dropped the __ prefix but forget to update the patch description. > _t is used for typedef simple types. It's unfortunate to have it > in such a macro. Ack. > Perhaps T or TYPE will suffice. Or perhaps we want > __GENMASK_Uxx() here? If no objection, I have a preference for GENMASK_TYPE(). >> types, and implement fixed-types versions of GENMASK() based on it. >> The fixed-type version allows more strict checks to the min/max values >> accepted, which is useful for defining registers like implemented by >> i915 and xe drivers with their REG_GENMASK*() macros. >> >> The strict checks rely on shift-count-overflow compiler check to fail >> the build if a number outside of the range allowed is passed. >> Example: >> >> #define FOO_MASK GENMASK_U32(33, 4) >> >> will generate a warning like: >> >> ../include/linux/bits.h:41:31: error: left shift count >= width of type [-Werror=shift-count-overflow] >> 41 | (((t)~0ULL - ((t)(1) << (l)) + 1) & \ >> | ^~ > > ... > >> + * __GENMASK_U*() depends on BITS_PER_TYPE() which would not work in the asm > > Where are the double underscore variants? I see it only for U128. Same as above. The description is incorrect. I will fix this in v5. >> + * code as BITS_PER_TYPE() relies on sizeof(), something not available in >> + * asm. Nethertheless, the concept of fixed width integers is a C thing which >> + * does not apply to assembly code. Yours sincerely, Vincent Mailhol
