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?
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
