On Sat, 5 Jun 2021, Michael Schmitz wrote: > Am 04.06.2021 um 19:54 schrieb Geert Uytterhoeven: > > > > I have to wonder whether there is a nice simple definition for > > > > MULTI_ISA. > > > > > > As I understand it, MULTI_ISA means that different byte orders > > > and/or different address translations need to be used in the same > > > kernel, so all that cannot be decided at build time. > > > > > > As long as there is only a single platform that will use this code > > > (ISA only used on a single platform, and neither Atari IDE nor > > > EtherNEC used), MULTI_ISA is not needed. > > > > > > If we have Kconfig symbols for 'single platform only', and > > > 'multi-platform ISA use', that might be shorter to write and easier > > > to understand. Geert? > > > > It would be nice to have that automatically, like with the current > > MULTI_ISA define (and all the MACH_* in > > arch/m68k/include/asm/setup.h). Perhaps we should extend kconfig > > syntax to define a group of related symbols, and to automatically > > generate CONFIG_FOO_MULTI or CONFIG_FOO_SINGLE (and even > > CONFIG_BAR_ONLY?) symbols? > > I take it this is not supported by our current Kconfig syntax? > That may be because CPP hacking is seen as a competitive sport in some circles. > > group ISA > > item ATARI_ROM_ISA > > item AMIGA_PCMCIA > > item Q40 > > > > => CONFIG_ISA_MULTI or CONFIG_ISA_SINGLE (+ e.g. ATARI_ROM_ISA_ONLY > > if appropriate). > > Since the items may be bools or tristates, it not clear what type the group has. Anyway, I see that we can already write this: #define IS_MULTI(a,b) __or(IS_ENABLED(a), IS_ENABLED(b)) So maybe we just need an exclusive-OR macro to go with the other operators defined in include/linux/kconfig.h? Then we could write this: #define IS_SINGLE(a,b) __xor(IS_ENABLED(a), IS_ENABLED(b)) But these only work for a 2-way group. Extending them to N-way groups is beyond my CPP abilities. It probably requires N-way __or() and __xor()...
