Hi, all, On Tue, Jul 12, 2022 at 6:15 PM WANG Xuerui <kernel@xxxxxxxxxx> wrote: > > Hi Geert and Huacai, > > On 2022/7/12 17:13, Geert Uytterhoeven wrote: > > Hi Huacai, > > > > On Tue, Jul 12, 2022 at 11:08 AM Huacai Chen <chenhuacai@xxxxxxxxx> wrote: > >> On Tue, Jul 12, 2022 at 5:01 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > >>> On Tue, Jul 12, 2022 at 10:53 AM Huacai Chen <chenhuacai@xxxxxxxxx> wrote: > >>>> On Tue, Jul 12, 2022 at 4:33 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > >>>>> On Tue, Jul 12, 2022 at 9:53 AM Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote: > >>>>>> When CONFIG_CPUMASK_OFFSTACK and CONFIG_DEBUG_PER_CPU_MAPS is selected, > >>>>> DEBUG_PER_CPU_MAPS depends on SMP, which is not supported on m68k, > >>>>> and thus cannot be enabled. > >>>> This patch is derived from MIPS and LoongArch, I search all > >>>> architectures and change those that look the same as MIPS and > >>>> LoongArch. > >>>> And the warning message below is also a copy-paste from LoongArch, sorry. > >>>> > >>>> Since M68K doesn't support SMP, then this patch seems to make no > >>>> difference, but does it make sense to keep consistency across all > >>>> architectures? > >>> Yes, having consistency is good. But that should be mentioned in the > >>> patch description, instead of a scary warning CCed to stable ;-) > >>> > >>> BTW, you probably want to update the other copy of c_start() in > >>> arch/m68k/kernel/setup_mm.c, too. > >> For no-SMP architectures, it seems c_start() in > >> arch/m68k/kernel/setup_mm.c is more reasonable (just use 1, neither > >> NR_CPUS, nor nr_cpu_ids)? > > The advantage of using nr_cpu_ids() is that this is one place less > > to update when adding SMP support later... > > Hmm, so I've been watching m68k development lately (although not as > closely as I'd like to, due to lack of vintage hardware at hand), given > the current amazing momentum all the hobbyists/developers have been > contributing to, SMP is well within reach... > > But judging from the intent of this patch series (fixing WARNs on > certain configs), and that the triggering condition is currently > impossible on m68k (and other non-SMP) platforms, I think cleanups for > such arches could come as a separate patch series later. I think the > m68k refactoring is reasonable after all, due to my observation above, > but for the other non-SMP arches we may want to wait for the respective > maintainers' opinions. It seems that the best solution is only fix architectures with SMP support and leave others (m68k, microblaze, um) as is. :) Huacai >
