Date: Tue, 15 Jan 2008 12:43:29 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-acpi@freebsd.org, Leo Bicknell <bicknell@ufp.org> Subject: Re: kern/119675: [acpi] apic_hpet0 probe causes divide by zero kernel panic Message-ID: <200801151243.30323.jhb@freebsd.org> In-Reply-To: <200801151640.m0FGe4hT005360@freefall.freebsd.org> References: <200801151640.m0FGe4hT005360@freefall.freebsd.org>
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On Tuesday 15 January 2008 11:40:04 am Leo Bicknell wrote:
> The following reply was made to PR kern/119675; it has been noted by GNATS.
>
> From: Leo Bicknell <bicknell@ufp.org>
> To: John Baldwin <jhb@FreeBSD.org>
> Cc: bug-followup@FreeBSD.org
> Subject: Re: kern/119675: [acpi] apic_hpet0 probe causes divide by zero kernel panic
> Date: Tue, 15 Jan 2008 11:33:14 -0500
>
> In a message written on Tue, Jan 15, 2008 at 10:13:07AM -0500, John Baldwin wrote:
> > You can try the patch below. It fixes a couple of places where we don't
> > honor the spec (we don't shut it off in S1 and S2 as required and we don't
> > preserve reserved bits in the global configuration register). It also
> > fails the attach if the period is zero which should fix your panic and
> > just leave you with no HPET.
>
> Good news and bad news.
>
> With the patch "invalid period" is printed out, so I believe it's
> correctly detecting the hpet0 issue.
>
> However, I immediately get an "integer divide fault while in kernel
> mode" panic and the boot still fails. I tried with boot -v and the
> message is right after the "invalid period", so I'm not quite sure
> what's causing it.
>
> Any recomendations, other than setting up a kernel debugger to see where
> it's coming from?
I forgot to include a return() statement to make it actually fail the attach.
My bad. Updated patch below:
--- //depot/vendor/freebsd/src/sys/dev/acpica/acpi_hpet.c 2007/10/09 07:52:34
+++ //depot/user/jhb/acpipci/dev/acpica/acpi_hpet.c 2008/01/15 17:42:12
@@ -82,6 +82,24 @@
return (bus_read_4(sc->mem_res, HPET_OFFSET_VALUE));
}
+static void
+hpet_enable(struct acpi_hpet_softc *sc)
+{
+ uint32_t val;
+
+ val = bus_read_4(sc->mem_res, HPET_OFFSET_ENABLE);
+ bus_write_4(sc->mem_res, HPET_OFFSET_ENABLE, val | 1);
+}
+
+static void
+hpet_disable(struct acpi_hpet_softc *sc)
+{
+ uint32_t val;
+
+ val = bus_read_4(sc->mem_res, HPET_OFFSET_ENABLE);
+ bus_write_4(sc->mem_res, HPET_OFFSET_ENABLE, val & ~1);
+}
+
/* Discover the HPET via the ACPI table of the same name. */
static void
acpi_hpet_identify(driver_t *driver, device_t parent)
@@ -166,10 +184,17 @@
}
/* Be sure timer is enabled. */
- bus_write_4(sc->mem_res, HPET_OFFSET_ENABLE, 1);
+ hpet_enable(sc);
/* Read basic statistics about the timer. */
val = bus_read_4(sc->mem_res, HPET_OFFSET_PERIOD);
+ if (val == 0) {
+ device_printf(dev, "invalid period\n");
+ hpet_disable(sc);
+ bus_free_resource(dev, SYS_RES_MEMORY, sc->mem_res);
+ return (ENXIO);
+ }
+
freq = (1000000000000000LL + val / 2) / val;
if (bootverbose) {
val = bus_read_4(sc->mem_res, HPET_OFFSET_INFO);
@@ -192,7 +217,7 @@
val2 = bus_read_4(sc->mem_res, HPET_OFFSET_VALUE);
if (val == val2) {
device_printf(dev, "HPET never increments, disabling\n");
- bus_write_4(sc->mem_res, HPET_OFFSET_ENABLE, 0);
+ hpet_disable(sc);
bus_free_resource(dev, SYS_RES_MEMORY, sc->mem_res);
return (ENXIO);
}
@@ -214,13 +239,29 @@
}
static int
+acpi_hpet_suspend(device_t dev)
+{
+ struct acpi_hpet_softc *sc;
+
+ /*
+ * Disable the timer during suspend. The timer will not lose
+ * its state in S1 or S2, but we are required to disable
+ * it.
+ */
+ sc = device_get_softc(dev);
+ hpet_disable(sc);
+
+ return (0);
+}
+
+static int
acpi_hpet_resume(device_t dev)
{
struct acpi_hpet_softc *sc;
/* Re-enable the timer after a resume to keep the clock advancing. */
sc = device_get_softc(dev);
- bus_write_4(sc->mem_res, HPET_OFFSET_ENABLE, 1);
+ hpet_enable(sc);
return (0);
}
@@ -260,6 +301,7 @@
DEVMETHOD(device_probe, acpi_hpet_probe),
DEVMETHOD(device_attach, acpi_hpet_attach),
DEVMETHOD(device_detach, acpi_hpet_detach),
+ DEVMETHOD(device_suspend, acpi_hpet_suspend),
DEVMETHOD(device_resume, acpi_hpet_resume),
{0, 0}
--
John Baldwin
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