[PATCH] acpi: try to trust cpu_index from x86_cpu_to_apicid

[PATCH] acpi: try to trust cpu_index from x86_cpu_to_apicid

[Baoquan He]

In smp with multi cpus, when enter into kdump kernel with only 1 cpu,
a warning message is printed out:

acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor

In this case kdump kernel use the same ACPI tables as 1st kernel,
means lapic information is got from MADT. The acpi_id related to
this cpu index and lapic_id may not be 0, so the code to assign
value to cpu_index is not correct in this case per cpu0_initialized.
cpu index stored in x86_cpu_to_apicid need be respected.

Now fix it in this patch per boot_cpu_physical_apicid. When cpu index
related to boot_cpu_physical_apicid is not stored in x86_cpu_to_apicid,
then we can say this is UP system running SMP kernel with no LAPIC in MADT

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 drivers/acpi/acpi_processor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index c29c2c3..1ae460c 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -267,7 +267,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
 	pr->apic_id = apic_id;
 
 	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
-	if (!cpu0_initialized) {
+	if (!cpu0_initialized && (boot_cpu_physical_apicid == pr->apic_id)) {
 		cpu0_initialized = 1;
 		/* Handle UP system running SMP kernel, with no LAPIC in MADT */
 		if ((cpu_index == -1) && (num_online_cpus() == 1))
-- 
1.8.5.3

Re: [PATCH] acpi: try to trust cpu_index from x86_cpu_to_apicid

[Rafael J. Wysocki]

On Tuesday, April 15, 2014 07:55:54 AM Baoquan He wrote:
> In smp with multi cpus, when enter into kdump kernel with only 1 cpu,
> a warning message is printed out:
> 
> acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor
> 
> In this case kdump kernel use the same ACPI tables as 1st kernel,
> means lapic information is got from MADT. The acpi_id related to
> this cpu index and lapic_id may not be 0, so the code to assign
> value to cpu_index is not correct in this case per cpu0_initialized.
> cpu index stored in x86_cpu_to_apicid need be respected.
> 
> Now fix it in this patch per boot_cpu_physical_apicid. When cpu index
> related to boot_cpu_physical_apicid is not stored in x86_cpu_to_apicid,
> then we can say this is UP system running SMP kernel with no LAPIC in MADT

Why don't you fix the warning message instead to cover this case too? 

> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  drivers/acpi/acpi_processor.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index c29c2c3..1ae460c 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -267,7 +267,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
>  	pr->apic_id = apic_id;
>  
>  	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
> -	if (!cpu0_initialized) {
> +	if (!cpu0_initialized && (boot_cpu_physical_apicid == pr->apic_id)) {
>  		cpu0_initialized = 1;
>  		/* Handle UP system running SMP kernel, with no LAPIC in MADT */
>  		if ((cpu_index == -1) && (num_online_cpus() == 1))
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] acpi: try to trust cpu_index from x86_cpu_to_apicid

[Baoquan He]

On 04/21/14 at 10:51pm, Rafael J. Wysocki wrote:
> On Tuesday, April 15, 2014 07:55:54 AM Baoquan He wrote:
> > In smp with multi cpus, when enter into kdump kernel with only 1 cpu,
> > a warning message is printed out:
> > 
> > acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor
> > 
> > In this case kdump kernel use the same ACPI tables as 1st kernel,
> > means lapic information is got from MADT. The acpi_id related to
> > this cpu index and lapic_id may not be 0, so the code to assign
> > value to cpu_index is not correct in this case per cpu0_initialized.
> > cpu index stored in x86_cpu_to_apicid need be respected.
> > 
> > Now fix it in this patch per boot_cpu_physical_apicid. When cpu index
> > related to boot_cpu_physical_apicid is not stored in x86_cpu_to_apicid,
> > then we can say this is UP system running SMP kernel with no LAPIC in MADT
> 
> Why don't you fix the warning message instead to cover this case too? 


Hi Rafael,

Thanks for replying.

In kdump case, that warning message is printed out just because the
assignation is not correct. 

E.g on that machine where this bug was reported, there are 16 cpus. In
normal kernel their information is stored in acpi MADT, and all of them
is present in system. However when crash happened, the cpu which crash
happened on will reboot. That reboot is a warm one, skip BIOS step.
And currently "nr_cpus=1" is need be  added into cmdline of kdump
kernel. The restriction of only 1 cpu is a long story for kdump, since
if crash happend on AP, if multi-cpu is not disabled, that AP will
reboot and send INIT IPI to BSP of 1st kernel, that will cause a
immediate reboot to BIOS which is a cpu hw behavior.

So when kdump kernel startup with "nr_cpus=1", it will use ACPI
information stored by BIOS step of 1st kernel, there are 16 lapic.
Below are message printed by acpi_register_lapic() when acpi handle MADT
table related to cpu and lapic. From these printed message, the present
cpu in kdump kernel has a acpi_id=0x0c and lapic_id=0x24. 

Then when scan acpi device, all cpus detected by acpi will be handled by
acpi_processor_add(). So the old code will directly assign the
cpu_index as 0 per the variable cpu0_initialized though
x86_cpu_to_apicid stored cpu 0 and its related apicid which is 0x24.
This will cause two acpi_device (acpi_id 0 and acpi_id 0x0c) have the
same cpu_index 0, then that warning message will be printed out since a
check found  per_cpu(processor_device_array, 0) has been assigned.

So I think it's a code bug, sould be fixed by correct checking.


[    0.000000] ACPI: LAPIC (acpi_id[0x00] lapic_id[0x10] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cpu.  Processor 0/0x10 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x08] lapic_id[0x20] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cpu.  Processor 1/0x20 ig.
[    0.000000] ACPI: LAPIC (acpi_id[0x01] lapic_id[0x11] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cpu.  Processor 2/0x11 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x09] lapic_id[0x21] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cpu.  Processor 3/0x21 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x02] lapic_id[0x12] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cp
[    0.000000] ACPI: LAPIC (acpi_id[0x0a] lapic_id[0x22] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cpu.  Processor 5/0x22 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x03] lapic_id[0x13] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cpu.  Processor 6/0x13 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x0b] lapic_id[0x23] enabled)
[    0.000000] ACPICPUS/possible_cpus limit of 1 almost reached. Keeping
one slot for boot cpu.  Processor 7/0x23 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x04] lapic_id[0x14] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 almost reached.
Keeping one slot for boot cpu.  Processor 8/0x14 ignored.

[    0.000000] ACPI: LAPIC (acpi_id[0x0c] lapic_id[0x24] enabled)

[    0.000000] ACPI: LAPIC (acpi_id[ lapic_id[0x15] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 reached.
Processor 10/0x15 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x0d] lapic_id[0x25] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 reached.
Processor 11/0x25 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x06] l 0.000000] ACPI:
NR_CPUS/possible_cpus limit of 1 reached.  Processor 12/0x16 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x0e] lapic_id[0x26] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 reached.
Processor 13/0x26 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x07] lapic_id[0x17] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit of 1 reached.
Processor 14/0x17 ignored.
[    0.000000] ACPI: LAPIC (acpi_id[0x0f] lapic_id[0x27] enabled)
[    0.000000] ACPI: NR_CPUS/possible_cpus limit ofached.  Processor
15/0x27 ignored.

Thanks
Baoquan

Re: [PATCH] acpi: try to trust cpu_index from x86_cpu_to_apicid

[Baoquan He]

On 04/21/14 at 10:51pm, Rafael J. Wysocki wrote:
> On Tuesday, April 15, 2014 07:55:54 AM Baoquan He wrote:
> > In smp with multi cpus, when enter into kdump kernel with only 1 cpu,
> > a warning message is printed out:
> > 
> > acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor
> > 
> > In this case kdump kernel use the same ACPI tables as 1st kernel,
> > means lapic information is got from MADT. The acpi_id related to
> > this cpu index and lapic_id may not be 0, so the code to assign
> > value to cpu_index is not correct in this case per cpu0_initialized.
> > cpu index stored in x86_cpu_to_apicid need be respected.
> > 
> > Now fix it in this patch per boot_cpu_physical_apicid. When cpu index
> > related to boot_cpu_physical_apicid is not stored in x86_cpu_to_apicid,
> > then we can say this is UP system running SMP kernel with no LAPIC in MADT
> 
> Why don't you fix the warning message instead to cover this case too? 
> 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  drivers/acpi/acpi_processor.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> > index c29c2c3..1ae460c 100644
> > --- a/drivers/acpi/acpi_processor.c
> > +++ b/drivers/acpi/acpi_processor.c
> > @@ -267,7 +267,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
> >  	pr->apic_id = apic_id;
> >  
> >  	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
> > -	if (!cpu0_initialized) {
> > +	if (!cpu0_initialized && (boot_cpu_physical_apicid == pr->apic_id)) {

Self NACK this patch.

Since this check should be limited on no LAPIC in MADT, so acpi_lapic is
better for this. Will repost after test.

Hi Rafael,

Do you have any suggestion on this fix?

Thanks
Baoquan

[Patch v2] lapic need be checked if available when initialize acpi processor id

[Baoquan He]

In acpi_processor_get_info(), acpi processor info is initialized including
id, namely cpu index. Currently, if on UP system running SMP kerenl with
no LAPIC in MADT, cpu0_initialized is checked if acpi processor id is
initialized.

However this check maybe is not correct for kdump kernel. Most of time
only 1 CPU is supported because of known problems. So in 1st kernel
multiple CPUs are present, then crash happened in one specific CPU,
say 2nd CPU. Then it jump into kdump kernel with "nr_cpus=1" specified
in cmdline. In this situation, since kdump kernel is warm reset, it will
reuse the ACPI resource passed from crashed kernel directly, namely 1st
kernel. It means in MADT all LAPIC is enabled while only 1 CPU is
present in running system. The kdump kernel usually is the same as the
crashed 1st kernel. So now in kdump kernel, x86_cpu_to_apicid stored the
apicid and its related cpu id. If only check cpu0_initialized, it will
assign 0 to the acpi processor id of 1st CPU, it's not correct.

So in this patch, check acpi_lapic too. If acpi_lapic is 0, then LAPIC in
MADT is not available, assigne 0 to the handling acpi processor. If
acpi_lapic is 1, then LAPIC in MADT is available, let's get apic processor
id from x86_cpu_to_apicid.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 drivers/acpi/acpi_processor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index c29c2c3..33f934d 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -267,7 +267,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
 	pr->apic_id = apic_id;
 
 	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
-	if (!cpu0_initialized) {
+	if (!cpu0_initialized && !acpi_lapic) {
 		cpu0_initialized = 1;
 		/* Handle UP system running SMP kernel, with no LAPIC in MADT */
 		if ((cpu_index == -1) && (num_online_cpus() == 1))
-- 
1.8.5.3

Re: [Patch v2] lapic need be checked if available when initialize acpi processor id

[Baoquan He]

Hi Rafael,

Thanks for previous review for v1. Later on I thought acpi_lapic is
more suitable for checking whether LAPIC in MADT is available, and it can
hanlde both the UP system running SMP kernel with no LAPIC in MADT and kdump
kernel after multiple CPUs system crashed on non-1st CPU.

I tested the 1st case by addding "disableapic nr_cpus=1" into cmdline
of SMP kenrel, and it works. For 2nd case, it works too, below warning
message is not printed any more. 

acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor

Do you like this idea?

Thanks
Baoquan

On 04/30/14 at 01:55pm, Baoquan He wrote:
> In acpi_processor_get_info(), acpi processor info is initialized including
> id, namely cpu index. Currently, if on UP system running SMP kerenl with
> no LAPIC in MADT, cpu0_initialized is checked if acpi processor id is
> initialized.
> 
> However this check maybe is not correct for kdump kernel. Most of time
> only 1 CPU is supported because of known problems. So in 1st kernel
> multiple CPUs are present, then crash happened in one specific CPU,
> say 2nd CPU. Then it jump into kdump kernel with "nr_cpus=1" specified
> in cmdline. In this situation, since kdump kernel is warm reset, it will
> reuse the ACPI resource passed from crashed kernel directly, namely 1st
> kernel. It means in MADT all LAPIC is enabled while only 1 CPU is
> present in running system. The kdump kernel usually is the same as the
> crashed 1st kernel. So now in kdump kernel, x86_cpu_to_apicid stored the
> apicid and its related cpu id. If only check cpu0_initialized, it will
> assign 0 to the acpi processor id of 1st CPU, it's not correct.
> 
> So in this patch, check acpi_lapic too. If acpi_lapic is 0, then LAPIC in
> MADT is not available, assigne 0 to the handling acpi processor. If
> acpi_lapic is 1, then LAPIC in MADT is available, let's get apic processor
> id from x86_cpu_to_apicid.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  drivers/acpi/acpi_processor.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index c29c2c3..33f934d 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -267,7 +267,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
>  	pr->apic_id = apic_id;
>  
>  	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
> -	if (!cpu0_initialized) {
> +	if (!cpu0_initialized && !acpi_lapic) {
>  		cpu0_initialized = 1;
>  		/* Handle UP system running SMP kernel, with no LAPIC in MADT */
>  		if ((cpu_index == -1) && (num_online_cpus() == 1))
> -- 
> 1.8.5.3
> 

Re: [Patch v2] lapic need be checked if available when initialize acpi processor id

[Rafael J. Wysocki]

On Wednesday, April 30, 2014 01:55:03 PM Baoquan He wrote:
> In acpi_processor_get_info(), acpi processor info is initialized including
> id, namely cpu index. Currently, if on UP system running SMP kerenl with
> no LAPIC in MADT, cpu0_initialized is checked if acpi processor id is
> initialized.
> 
> However this check maybe is not correct for kdump kernel. Most of time
> only 1 CPU is supported because of known problems. So in 1st kernel
> multiple CPUs are present, then crash happened in one specific CPU,
> say 2nd CPU. Then it jump into kdump kernel with "nr_cpus=1" specified
> in cmdline. In this situation, since kdump kernel is warm reset, it will
> reuse the ACPI resource passed from crashed kernel directly, namely 1st
> kernel. It means in MADT all LAPIC is enabled while only 1 CPU is
> present in running system. The kdump kernel usually is the same as the
> crashed 1st kernel. So now in kdump kernel, x86_cpu_to_apicid stored the
> apicid and its related cpu id. If only check cpu0_initialized, it will
> assign 0 to the acpi processor id of 1st CPU, it's not correct.
> 
> So in this patch, check acpi_lapic too. If acpi_lapic is 0, then LAPIC in
> MADT is not available, assigne 0 to the handling acpi processor. If
> acpi_lapic is 1, then LAPIC in MADT is available, let's get apic processor
> id from x86_cpu_to_apicid.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  drivers/acpi/acpi_processor.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index c29c2c3..33f934d 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -267,7 +267,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
>  	pr->apic_id = apic_id;
>  
>  	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
> -	if (!cpu0_initialized) {
> +	if (!cpu0_initialized && !acpi_lapic) {

That doesn't compile:

drivers/acpi/acpi_processor.c:271:28: error: 'acpi_lapic' undeclared (first use in this function)

>  		cpu0_initialized = 1;
>  		/* Handle UP system running SMP kernel, with no LAPIC in MADT */
>  		if ((cpu_index == -1) && (num_online_cpus() == 1))
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [Patch v2] lapic need be checked if available when initialize acpi processor id

[Rafael J. Wysocki]

On Wednesday, April 30, 2014 02:03:03 PM Baoquan He wrote:
> Hi Rafael,

Hi,

> Thanks for previous review for v1. Later on I thought acpi_lapic is
> more suitable for checking whether LAPIC in MADT is available, and it can
> hanlde both the UP system running SMP kernel with no LAPIC in MADT and kdump
> kernel after multiple CPUs system crashed on non-1st CPU.
> 
> I tested the 1st case by addding "disableapic nr_cpus=1" into cmdline
> of SMP kenrel, and it works. For 2nd case, it works too, below warning
> message is not printed any more. 
> 
> acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor
> 
> Do you like this idea?

Well, I don't hate it, but you need to make the code build in all
configurations (including ia64).

Thanks!


> On 04/30/14 at 01:55pm, Baoquan He wrote:
> > In acpi_processor_get_info(), acpi processor info is initialized including
> > id, namely cpu index. Currently, if on UP system running SMP kerenl with
> > no LAPIC in MADT, cpu0_initialized is checked if acpi processor id is
> > initialized.
> > 
> > However this check maybe is not correct for kdump kernel. Most of time
> > only 1 CPU is supported because of known problems. So in 1st kernel
> > multiple CPUs are present, then crash happened in one specific CPU,
> > say 2nd CPU. Then it jump into kdump kernel with "nr_cpus=1" specified
> > in cmdline. In this situation, since kdump kernel is warm reset, it will
> > reuse the ACPI resource passed from crashed kernel directly, namely 1st
> > kernel. It means in MADT all LAPIC is enabled while only 1 CPU is
> > present in running system. The kdump kernel usually is the same as the
> > crashed 1st kernel. So now in kdump kernel, x86_cpu_to_apicid stored the
> > apicid and its related cpu id. If only check cpu0_initialized, it will
> > assign 0 to the acpi processor id of 1st CPU, it's not correct.
> > 
> > So in this patch, check acpi_lapic too. If acpi_lapic is 0, then LAPIC in
> > MADT is not available, assigne 0 to the handling acpi processor. If
> > acpi_lapic is 1, then LAPIC in MADT is available, let's get apic processor
> > id from x86_cpu_to_apicid.
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  drivers/acpi/acpi_processor.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> > index c29c2c3..33f934d 100644
> > --- a/drivers/acpi/acpi_processor.c
> > +++ b/drivers/acpi/acpi_processor.c
> > @@ -267,7 +267,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
> >  	pr->apic_id = apic_id;
> >  
> >  	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
> > -	if (!cpu0_initialized) {
> > +	if (!cpu0_initialized && !acpi_lapic) {
> >  		cpu0_initialized = 1;
> >  		/* Handle UP system running SMP kernel, with no LAPIC in MADT */
> >  		if ((cpu_index == -1) && (num_online_cpus() == 1))
> --
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [Patch v2] lapic need be checked if available when initialize acpi processor id

[Baoquan He]

On 04/30/14 at 10:13pm, Rafael J. Wysocki wrote:
> On Wednesday, April 30, 2014 02:03:03 PM Baoquan He wrote:
> > Hi Rafael,
> 
> Hi,
> 
> > Thanks for previous review for v1. Later on I thought acpi_lapic is
> > more suitable for checking whether LAPIC in MADT is available, and it can
> > hanlde both the UP system running SMP kernel with no LAPIC in MADT and kdump
> > kernel after multiple CPUs system crashed on non-1st CPU.
> > 
> > I tested the 1st case by addding "disableapic nr_cpus=1" into cmdline
> > of SMP kenrel, and it works. For 2nd case, it works too, below warning
> > message is not printed any more. 
> > 
> > acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor
> > 
> > Do you like this idea?
> 
> Well, I don't hate it, but you need to make the code build in all
> configurations (including ia64).
> 
Hi Rafael,

Sorry about this, I didn't realize acpi_lapic is for x86 only. And ia64
uses it too. About this bug, it should exist in ia64 too. After checking
code, introducing acpi_lapic into ia64 is a solution, I will try to find
a ia64 machine to test this though it's a little difficult, since people
around didn't test ia64 recently.

Any suggestion  or comment?

Thanks
Baoquan

Re: [Patch v2] lapic need be checked if available when initialize acpi processor id

[Rafael J. Wysocki]

On Friday, May 02, 2014 04:51:46 PM Baoquan He wrote:
> On 04/30/14 at 10:13pm, Rafael J. Wysocki wrote:
> > On Wednesday, April 30, 2014 02:03:03 PM Baoquan He wrote:
> > > Hi Rafael,
> > 
> > Hi,
> > 
> > > Thanks for previous review for v1. Later on I thought acpi_lapic is
> > > more suitable for checking whether LAPIC in MADT is available, and it can
> > > hanlde both the UP system running SMP kernel with no LAPIC in MADT and kdump
> > > kernel after multiple CPUs system crashed on non-1st CPU.
> > > 
> > > I tested the 1st case by addding "disableapic nr_cpus=1" into cmdline
> > > of SMP kenrel, and it works. For 2nd case, it works too, below warning
> > > message is not printed any more. 
> > > 
> > > acpi LNXCPU:0a: BIOS reported wrong ACPI id 0 for the processor
> > > 
> > > Do you like this idea?
> > 
> > Well, I don't hate it, but you need to make the code build in all
> > configurations (including ia64).
> > 
> Hi Rafael,
> 
> Sorry about this, I didn't realize acpi_lapic is for x86 only. And ia64
> uses it too. About this bug, it should exist in ia64 too. After checking
> code, introducing acpi_lapic into ia64 is a solution, I will try to find
> a ia64 machine to test this though it's a little difficult, since people
> around didn't test ia64 recently.
> 
> Any suggestion  or comment?

The plan sounds good, thanks!


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.