> Date: Thu, 5 Oct 2023 04:10:10 +0000
> From: Klemens Nanni <k...@openbsd.org>
>
> On Mon, Sep 25, 2023 at 01:33:31PM +0000, Klemens Nanni wrote:
> > On Tue, Jul 25, 2023 at 01:30:43PM +0300, Slava Voronzoff wrote:
> > > Hi, pinging and refreshing this patch
> > >
> > > What it does:
> > > allow arm64 cpus to break from the loop of waiting to start core and
> > > drop to DDB or OS.
> > >
> > > Patch based on same concept in amd64 cpu.c
> > >
> > > Any suggestions? Good to go?
> >
> > So instead of waiting possibly forever for secondary CPUs to come up,
> > you can continue debug the system and/or continue boot with less CPUs.
> >
> > Apart from the trailing empty line you introduce, the approach does
> > match amd64 (down to the for loop lacking a space after semicolon).
> >
> > That allows making progress on these machines and I don't see a downside,
> > so OK kn modulo the empty line.
> >
> > Any input from our arm64 hackers?
> >
> > Same diff ten days ago:
> > https://marc.info/?l=openbsd-bugs&m=169465443200821&w=2
>
> Anyone?
Really, if those secondary CPUs don't come up, your system is beyond
repair. You need to do some low-level debugging at that point and DDB
isn't going to help you. So no, let's keep this code as simple as we
can.
> Index: sys/arch/arm64//arm64/cpu.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/arm64/arm64/cpu.c,v
> retrieving revision 1.98
> diff -u -p -r1.98 cpu.c
> --- sys/arch/arm64//arm64/cpu.c 10 Aug 2023 19:29:32 -0000 1.98
> +++ sys/arch/arm64//arm64/cpu.c 25 Sep 2023 13:24:39 -0000
> @@ -1096,6 +1096,8 @@ cpu_start_secondary(struct cpu_info *ci,
> void
> cpu_boot_secondary(struct cpu_info *ci)
> {
> + int i;
> +
> atomic_setbits_int(&ci->ci_flags, CPUF_GO);
> __asm volatile("dsb sy; sev" ::: "memory");
>
> @@ -1105,8 +1107,16 @@ cpu_boot_secondary(struct cpu_info *ci)
> */
> arm_send_ipi(ci, ARM_IPI_NOP);
>
> - while ((ci->ci_flags & CPUF_RUNNING) == 0)
> + for (i = 1000; (!(ci->ci_flags & CPUF_RUNNING)) && i>0;i--) {
> __asm volatile("wfe");
> + }
> + if (! (ci->ci_flags & CPUF_RUNNING)) {
> + printf("cpu %d failed to start\n", ci->ci_cpuid);
> +#if defined(MPDEBUG) && defined(DDB)
> + printf("dropping into debugger; continue from here to resume
> boot\n");
> + db_enter();
> +#endif
> + }
> }
>
> void
>
>
