Hi Thomas, Meelis
At 01/11/2018 02:34 AM, Thomas Gleixner wrote:
On Wed, 10 Jan 2018, Meelis Roos wrote:
On 3 of my test computers, boot hangs with 4.15 git kernels. So far I
have traced it down to 4.14.0 being good and 4.15-rc1 being bad (bisect
is slow because the computers are somwehat remote). Also because of
trying to find when it started, I have not tries newer than rc5
kernels.
The hang happens after Performance Events feature table has been printed
but before APIC initialization messages normally appear ("Enabling APIC
mode: Flat. Using 0 I/O APICs" or something like that).
It happens on at least 3 distinct computers:
* AMD Athlon with AMD 750 chipset
* P3 1 GHz with i815 chipset
* P4 1.7 GHz with SiS chipset
They all have have "lapic" parameter because they were telling me that
lapic has been disabled by BIOS and I re-enabled it with the parameter
to get apic timer interrupts. This worked up until 4.14.
None of the computers have IO-APICs.
Oh. Then it possibly falls into Dou's realm.
Dou?
Ah, This problem looks like what Ville reported[1].
Revert the commit b371ae0d4a19 ("x86/apic: Remove init_bsp_APIC()") may
make it work again.
But, I don't know the true reason.
In Linux v4.15-rc1+, apic->setup_apic_routing() has been called earlier,
So, I guess kernel may hang in some early initcall fuctions. we can add
"initcall_debug" option in the kernel command line for tracing initcalls
as they are executed.
[1] https://marc.info/?l=linux-kernel&m=151188084018443&w=2
Thanks,
dou.
--------------------------->8-----------------------------------
From: Ville Syrjälä <[email protected]>
This reverts commit b371ae0d4a194b178817b0edfb6a7395c7aec37a.
Causes my P3 UP machine to hang at boot with "lapic".
Cc: Dou Liyang <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Signed-off-by: Ville Syrjälä <[email protected]>
---
arch/x86/include/asm/apic.h | 1 +
arch/x86/kernel/apic/apic.c | 49
+++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/irqinit.c | 3 +++
3 files changed, 53 insertions(+)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index a9e57f08bfa6..98722773391d 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -136,6 +136,7 @@ extern void disconnect_bsp_APIC(int virt_wire_setup);
extern void disable_local_APIC(void);
extern void lapic_shutdown(void);
extern void sync_Arb_IDs(void);
+extern void init_bsp_APIC(void);
extern void apic_intr_mode_init(void);
extern void setup_local_APIC(void);
extern void init_apic_mappings(void);
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 6e272f3ea984..cec9aaea7f9d 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1286,6 +1286,55 @@ static int __init apic_intr_mode_select(void)
return APIC_SYMMETRIC_IO;
}
+/*
+ * An initial setup of the virtual wire mode.
+ */
+void __init init_bsp_APIC(void)
+{
+ unsigned int value;
+
+ /*
+ * Don't do the setup now if we have a SMP BIOS as the
+ * through-I/O-APIC virtual wire mode might be active.
+ */
+ if (smp_found_config || !boot_cpu_has(X86_FEATURE_APIC))
+ return;
+
+ /*
+ * Do not trust the local APIC being empty at bootup.
+ */
+ clear_local_APIC();
+
+ /*
+ * Enable APIC.
+ */
+ value = apic_read(APIC_SPIV);
+ value &= ~APIC_VECTOR_MASK;
+ value |= APIC_SPIV_APIC_ENABLED;
+
+#ifdef CONFIG_X86_32
+ /* This bit is reserved on P4/Xeon and should be cleared */
+ if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
+ (boot_cpu_data.x86 == 15))
+ value &= ~APIC_SPIV_FOCUS_DISABLED;
+ else
+#endif
+ value |= APIC_SPIV_FOCUS_DISABLED;
+ value |= SPURIOUS_APIC_VECTOR;
+ apic_write(APIC_SPIV, value);
+
+ /*
+ * Set up the virtual wire mode.
+ */
+ apic_write(APIC_LVT0, APIC_DM_EXTINT);
+ value = APIC_DM_NMI;
+ if (!lapic_is_integrated()) /* 82489DX */
+ value |= APIC_LVT_LEVEL_TRIGGER;
+ if (apic_extnmi == APIC_EXTNMI_NONE)
+ value |= APIC_LVT_MASKED;
+ apic_write(APIC_LVT1, value);
+}
+
/* Init the interrupt delivery mode for the BSP */
void __init apic_intr_mode_init(void)
{
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index 8da3e909e967..a539410c4ea9 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -61,6 +61,9 @@ void __init init_ISA_irqs(void)
struct irq_chip *chip = legacy_pic->chip;
int i;
+#if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)
+ init_bsp_APIC();
+#endif
legacy_pic->init(0);
for (i = 0; i < nr_legacy_irqs(); i++)
--
Thanks,
tglx
