* Len Brown <lenb@xxxxxxxxxx> wrote: > > > hlt_works_ok was X86_32 only, initialized to 1, and never cleared. > > > > > > On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no" > > > > I think you missed the valid usecase where an old CPU with broken halt is > > booted with the no-hlt boot parameter and does not want to crash in the HLT > > instruction. > > > > That "no-hlt" boot parameter does: > > > > arch/x86/kernel/cpu/bugs.c: boot_cpu_data.hlt_works_ok = 0; > > > > We can restrict compatibility, but *please* lets do it *explicitly*, not under > > some 'remove unused code' pretense ... > > > > Could you please list all CPU models that are affected? > > "no-hlt" existed only for 32-bit, and there were exactly zero > automatic invocations of it. Do we know whether a distro adds this to the boot line? Do we know about users relying on it. > "idle=poll" does the same thing -- sans change a line > in /proc/cpuinfo. It also has an effect on halt/poweroff, right? > Do we really need both? Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ... So please list the affected hardware and list the affected boot parameter explicitly, in a well-titled commit that phases out this (very likely unused) compatibility hack and *document* the idle=poll workaround for ancient hardware. There's still i386DX CPUs being manufactured these days - a 20+ years old CPU design is surprisingly resilient to spurious patent claims, for obvious reasons. Really, there's no need to do things by stealth. There's few things worse than doing the right thing for the wrong reason - it becomes a bad habit of subtly broken thinking quickly. Thanks, Ingo _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
