Date: Wed, 13 Feb 2019 22:09:44 -0800 From: Mark Millard <marklmi@yahoo.com> To: FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: Re: Some evidence about the PowerMac G5 multiprocessor boot hang ups with the modern VM_MAX_KERNEL_ADDRESS value Message-ID: <9FBCA729-CE80-44CD-8873-431853E55231@yahoo.com> In-Reply-To: <11680D15-D43D-4115-AF4F-5F6E4E0022C9@yahoo.com> References: <11680D15-D43D-4115-AF4F-5F6E4E0022C9@yahoo.com>
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[I provide additional bootverbose output for both a successful
boot and a failing one.]
On 2019-Feb-13, at 19:35, Mark Millard <marklmi at yahoo.com> wrote:
> I added some bootverbose messages to:
>=20
> static int
> powermac_smp_start_cpu(platform_t plat, struct pcpu *pc)
> (in /usr/src/sys/powerpc/powermac/platform_powermac.c )
>=20
> and:
>=20
> void
> machdep_ap_bootstrap(void)
> ( /usr/src/sys/powerpc/powerpc/mp_machdep.c )
>=20
> and:
>=20
> static void
> cpu_mp_unleash(void *dummy)
> ( /usr/src/sys/powerpc/powerpc/mp_machdep.c )
>=20
>=20
>=20
> The result was (typed from a image and
> showing normal messages too):
>=20
> Adding CPU 0, hwref=3Dcd38, awkae=3D1
> Waling up CPU 3 (dev=3Dc480)
> Before reset 4&0 for CPU 3, hwref=3Dc480, awake=3D0
> After reset 4&0 for CPU3, hwref=3Dc480, awake=3D0
> After attempted wait for awake CPU 3, hwref=3Dc480, awake=3D0
> cpu_mp_unleash after platform_smp_start_cpu and waiting: CPU3, =
hwref=3Dx480, awake=3D0
> cpu_mp_unleash adding pc_cpuid to stopped_cpus: CPU 3 (dev=3Dc480)
> Waking up CPU 2 (dev=3Dc768)
> Before reset 4&0 for CPU 2, hwref=3Dc768, awake=3D0
>=20
> There is no more text.
>=20
> Part of the information is what messages were not displayed.
>=20
> Some notes:
>=20
> Only CPU 0 gots a: smp_cpus++ (resulting in 1).
>=20
> There is no solid evidence for if machdep_ap_bootstrap was
> ever used for CPU 3 or CPU 2.
>=20
> The wait loop after the platform_smp_start_cpu call in
> cpu_mp_unleash for CPU 3 is not used. The code in
> machdep_ap_bootstrap:
>=20
> PCPU_SET(awake, 1);
> __asm __volatile("msync; isync");
>=20
> did not have a visible effect on the pc->pc_awake value in
> platform_smp_start_cpu and cpu_mp_unleash. I have no
> unique evidence that it was executed at all.
>=20
> My messages added to machdep_ap_bootstrap were not displayed.
>=20
> platform_smp_start_cpu did not return for CPU 2.
> cpu_mp_unleash makes no more progress. In fact the
> 2 resets do not complete overall for CPU 2 (but did
> for CPU 3, even if it is unclear what code was
> executed):
>=20
> *rstvec =3D 4;
> powerpc_sync();
> (void)(*rstvec);
> powerpc_sync();
> DELAY(1);
> *rstvec =3D 0;
> powerpc_sync();
> (void)(*rstvec);
> powerpc_sync();
>=20
> I'll see about getting more information about the resets used.
>=20
>=20
>=20
> For reference for the added messages:
>=20
> # svnlite diff /usr/src/sys/powerpc/powermac/platform_powermac.c =
/usr/src/sys/powerpc/powerpc/mp_machdep.c
> Index: /usr/src/sys/powerpc/powermac/platform_powermac.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- /usr/src/sys/powerpc/powermac/platform_powermac.c (revision =
344018)
> +++ /usr/src/sys/powerpc/powermac/platform_powermac.c (working copy)
> @@ -371,6 +371,11 @@
> rstvec_virtbase =3D pmap_mapdev(0x80000000, PAGE_SIZE);
>=20
> rstvec =3D rstvec_virtbase + reset;
> +=20
> + if (bootverbose) // HACK!!!
> + printf("Before reset 4&0 for CPU %d, hwref=3D%jx, =
awake=3D%x\n",
> + pc->pc_cpuid, (uintmax_t)pc->pc_hwref,
> + pc->pc_awake);
>=20
> *rstvec =3D 4;
> powerpc_sync();
> @@ -382,10 +387,20 @@
> (void)(*rstvec);
> powerpc_sync();
>=20
> + if (bootverbose) // HACK!!!
> + printf("After reset 4&0 for CPU %d, hwref=3D%jx, =
awake=3D%x\n",
> + pc->pc_cpuid, (uintmax_t)pc->pc_hwref,
> + pc->pc_awake);
> +
> timeout =3D 10000;
> while (!pc->pc_awake && timeout--)
> DELAY(100);
>=20
> + if (bootverbose) // HACK!!!
> + printf("After attempted wait for awake CPU %d, =
hwref=3D%jx, awake=3D%x\n",
> + pc->pc_cpuid, (uintmax_t)pc->pc_hwref,
> + pc->pc_awake);
> +
> return ((pc->pc_awake) ? 0 : EBUSY);
> #else
> /* No SMP support */
> Index: /usr/src/sys/powerpc/powerpc/mp_machdep.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- /usr/src/sys/powerpc/powerpc/mp_machdep.c (revision 344018)
> +++ /usr/src/sys/powerpc/powerpc/mp_machdep.c (working copy)
> @@ -97,6 +97,9 @@
> /* Initialize decrementer */
> decr_ap_init();
>=20
> + if (bootverbose) // HACK!!!
> + printf("machdep_ap_bootstrap before ap_boot_mtx lock: =
AP CPU #%d launched\n", PCPU_GET(cpuid));
> +
> /* Serialize console output and AP count increment */
> mtx_lock_spin(&ap_boot_mtx);
> ap_awake++;
> @@ -109,6 +112,8 @@
>=20
> while(smp_started =3D=3D 0)
> ;
> + if (bootverbose) // HACK!!!
> + printf("machdep_ap_bootstrap after smp_started!=3D0: =
AP CPU #%d launched\n", PCPU_GET(cpuid));
>=20
> /* Start per-CPU event timers. */
> cpu_initclocks_ap();
> @@ -238,10 +243,19 @@
>=20
> ret =3D platform_smp_start_cpu(pc);
> if (ret =3D=3D 0) {
> + if (bootverbose) // HACK!!!
> + printf("cpu_mp_unleash =
attempting to wait for pc_awake: CPU %d, hwref=3D%jx, awake=3D%x\n",
> + pc->pc_cpuid, =
(uintmax_t)pc->pc_hwref,
> + pc->pc_awake);
> +
> timeout =3D 2000; /* wait 2sec for =
the AP */
> while (!pc->pc_awake && --timeout > 0)
> DELAY(1000);
> }
> + if (bootverbose) // HACK!!!
> + printf("cpu_mp_unleash after =
platform_smp_start_cpu and waiting: CPU %d, hwref=3D%jx, awake=3D%x\n",
> + pc->pc_cpuid, =
(uintmax_t)pc->pc_hwref,
> + pc->pc_awake);
> } else {
> pc->pc_awake =3D 1;
> }
> @@ -252,7 +266,13 @@
> pc->pc_awake);
> smp_cpus++;
> } else
> + { // HACK!!!
> + if (bootverbose) // HACK!!!
> + printf("cpu_mp_unleash adding =
pc_cpuid to stopped_cpus: CPU %d (dev=3D%x)\n",
> + pc->pc_cpuid, (int)pc->pc_hwref);
> CPU_SET(pc->pc_cpuid, &stopped_cpus);
> + } // HACK!!!
> +
> }
>=20
> ap_awake =3D 1;
>=20
I added some more bootverbose code.
A boot that completed showed:
Adding CPU 0, hwref=3Dcd38, awake=3D1
Trying to mount root from ufs:/dev/ufs/FBSDG5L2rootfs [rw,noatime]...
Waking up CPU 3 (dev=3Dc480)
powermac_smp_start_cpu 's OF_getprop for CPU 3, hwref=3Dc480, awake=3D0: =
res=3D4, reset=3D8c
powermac_smp_start_cpu for CPU 3, hwref=3Dc480, awake=3D0: =
rstvec_virtbase=3D0xe000000087fd2000
powermac_smp_start_cpu for CPU 3, hwref=3Dc480, awake=3D0: =
rstvec=3D0xe000000087fd208c
Before reset 4&0 for CPU 3, hwref=3Dc480, awake=3D0
After reset 4&0 for CPU 3, hwref=3Dc480, awake=3D0
After attempted wait for awake CPU 3, hwref=3Dc480, awake=3D1
cpu_mp_unleash attempting to wait for pc_awake: CPU 3, hwref=3Dc480, =
awake=3D1
cpu_mp_unleash after platform_smp_start_cpu and waiting: CPU 3, =
hwref=3Dc480, awake=3D1
Adding CPU 3, hwref=3Dc480, awake=3D1
Waking up CPU 2 (dev=3Dc768)
powermac_smp_start_cpu 's OF_getprop for CPU 2, hwref=3Dc768, awake=3D0: =
res=3D4, reset=3D8b
powermac_smp_start_cpu for CPU 2, hwref=3Dc768, awake=3D0: =
rstvec=3D0xe000000087fd208b
Before reset 4&0 for CPU 2, hwref=3Dc768, awake=3D0
After reset 4&0 for CPU 2, hwref=3Dc768, awake=3D0
After attempted wait for awake CPU 2, hwref=3Dc768, awake=3D1
cpu_mp_unleash attempting to wait for pc_awake: CPU 2, hwref=3Dc768, =
awake=3D1
cpu_mp_unleash after platform_smp_start_cpu and waiting: CPU 2, =
hwref=3Dc768, awake=3D1
Adding CPU 2, hwref=3Dc768, awake=3D1
Waking up CPU 1 (dev=3Dca50)
powermac_smp_start_cpu 's OF_getprop for CPU 1, hwref=3Dca50, awake=3D0: =
res=3D4, reset=3D8a
powermac_smp_start_cpu for CPU 1, hwref=3Dca50, awake=3D0: =
rstvec=3D0xe000000087fd208a
Before reset 4&0 for CPU 1, hwref=3Dca50, awake=3D0
After reset 4&0 for CPU 1, hwref=3Dca50, awake=3D0
After attempted wait for awake CPU 1, hwref=3Dca50, awake=3D1
cpu_mp_unleash attempting to wait for pc_awake: CPU 1, hwref=3Dca50, =
awake=3D1
cpu_mp_unleash after platform_smp_start_cpu and waiting: CPU 1, =
hwref=3Dca50, awake=3D1
Adding CPU 1, hwref=3Dca50, awake=3D1
machdep_ap_bootstrap before ap_boot_mtx lock: AP CPU #3 launched
machdep_ap_bootstrap before ap_boot_mtx lock: AP CPU #2 launched
machdep_ap_bootstrap before ap_boot_mtx lock: AP CPU #1 launched
SMP: AP CPU #3 launched
SMP: AP CPU #2 launched
SMP: AP CPU #1 launched
machdep_ap_bootstrap after smp_started!=3D0: AP CPU #2 launched
machdep_ap_bootstrap after smp_started!=3D0: AP CPU #3 launched
machdep_ap_bootstrap after smp_started!=3D0: AP CPU #1 launched
A failing boot is very similar but for awake values (and consequences)
and omitting much (the hang):
Adding CPU 0, hwref=3Dcd38, awake=3D1
Trying to mount root from ufs:/dev/ufs/FBSDG5L2rootfs [rw,noatime]...
Waking up CPU 3 (dev=3Dc480)
powermac_smp_start_cpu 's OF_getprop for CPU 3, hwref=3Dc480, awake=3D0: =
res=3D4, reset=3D8c
powermac_smp_start_cpu for CPU 3, hwref=3Dc480, awake=3D0: =
rstvec_virtbase=3D0xe000000087fd2000
powermac_smp_start_cpu for CPU 3, hwref=3Dc480, awake=3D0: =
rstvec=3D0xe000000087fd208c
Before reset 4&0 for CPU 3, hwref=3Dc480, awake=3D0
After reset 4&0 for CPU 3, hwref=3Dc480, awake=3D0
After attempted wait for awake CPU 3, hwref=3Dc480, awake=3D0
cpu_mp_unleash after platform_smp_start_cpu and waiting: CPU 3, =
hwref=3Dc480, awake=3D0
cpu_mp_unleash adding pc_cpuid to stopped_cpus: CPU 3 (dev=3Dc480)
Waking up CPU 2 (dev=3Dc768)
powermac_smp_start_cpu 's OF_getprop for CPU 2, hwref=3Dc768, awake=3D0: =
res=3D4, reset=3D8b
powermac_smp_start_cpu for CPU 2, hwref=3Dc768, awake=3D0: =
rstvec=3D0xe000000087fd208b
Before reset 4&0 for CPU 2, hwref=3Dc768, awake=3D0
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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