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[Patch v3 2/2] x86/acpi: Remove the repeated lapic address override entry parsing

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  [Patch v3 2/2] x86/acpi: Remove the repeated lapic address override entry parsing Baoquan He <bhe@redhat.com> - 2016-07-30 13:20 +0200
    Re: [Patch v3 2/2] x86/acpi: Remove the repeated lapic address  override entry parsing Ingo Molnar <mingo@kernel.org> - 2016-08-10 20:20 +0200
      Re: [Patch v3 2/2] x86/acpi: Remove the repeated lapic address  override entry parsing Baoquan He <bhe@redhat.com> - 2016-08-10 21:10 +0200

#1452673 — [Patch v3 2/2] x86/acpi: Remove the repeated lapic address override entry parsing

ACPI MADT has a 32-bit field providing lapic address at which
each processor can access its lapic information. MADT also contains
an optional entry to provide a 64-bit address to override the 32-bit
one. However the current code does the lapic address override entry
parsing twice. One is in early_acpi_boot_init() because AMD NUMA need
get boot_cpu_id earlier. The other is in acpi_boot_init() which parses
all MADT entries.

So in this patch remove the repeated code in the 2nd part. Meanwhile
print lapic override entry information like other MADT entry, this
will be added to boot log.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
v1->v2:
  -Remove the incorrect code comment above early_acpi_boot_init()
   as Rafael suggested.

v2->v3:
  -Spell out that lapic override entry information is added to boot
   log as Ingo suggested.

 arch/x86/kernel/acpi/boot.c | 17 ++---------------
 arch/x86/kernel/apic/apic.c |  2 +-
 2 files changed, 3 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 6738e5c..9f5b332 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -282,6 +282,8 @@ acpi_parse_lapic_addr_ovr(struct acpi_subtable_header * header,
 	if (BAD_MADT_ENTRY(lapic_addr_ovr, end))
 		return -EINVAL;
 
+	acpi_table_print_madt_entry(header);
+
 	acpi_lapic_addr = lapic_addr_ovr->address;
 
 	return 0;
@@ -998,21 +1000,6 @@ static int __init acpi_parse_madt_lapic_entries(void)
 	if (!boot_cpu_has(X86_FEATURE_APIC))
 		return -ENODEV;
 
-	/*
-	 * Note that the LAPIC address is obtained from the MADT (32-bit value)
-	 * and (optionally) overridden by a LAPIC_ADDR_OVR entry (64-bit value).
-	 */
-
-	count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC_OVERRIDE,
-				      acpi_parse_lapic_addr_ovr, 0);
-	if (count < 0) {
-		printk(KERN_ERR PREFIX
-		       "Error parsing LAPIC address override entry\n");
-		return count;
-	}
-
-	register_lapic_address(acpi_lapic_addr);
-
 	count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_SAPIC,
 				      acpi_parse_sapic, MAX_LOCAL_APIC);
 
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ac8d8ad..346ec91 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1801,7 +1801,7 @@ void __init register_lapic_address(unsigned long address)
 	if (!x2apic_mode) {
 		set_fixmap_nocache(FIX_APIC_BASE, address);
 		apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
-			    APIC_BASE, mp_lapic_addr);
+			    APIC_BASE, address);
 	}
 	if (boot_cpu_physical_apicid == -1U) {
 		boot_cpu_physical_apicid  = read_apic_id();
-- 
2.5.5

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#1459373 — Re: [Patch v3 2/2] x86/acpi: Remove the repeated lapic address override entry parsing

* Baoquan He <bhe@redhat.com> wrote:

> ACPI MADT has a 32-bit field providing lapic address at which
> each processor can access its lapic information. MADT also contains
> an optional entry to provide a 64-bit address to override the 32-bit
> one. However the current code does the lapic address override entry
> parsing twice. One is in early_acpi_boot_init() because AMD NUMA need
> get boot_cpu_id earlier. The other is in acpi_boot_init() which parses
> all MADT entries.
> 
> So in this patch remove the repeated code in the 2nd part. Meanwhile
> print lapic override entry information like other MADT entry, this
> will be added to boot log.

it is not at all clear to me from this changelog whether the change is supposed to 
change anything. If not then please spell it out explicitly:

  "This patch is not supposed to change any behavior."

Or so.

Thanks,

	Ingo

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#1459602 — Re: [Patch v3 2/2] x86/acpi: Remove the repeated lapic address override entry parsing

On 08/10/16 at 04:02pm, Ingo Molnar wrote:
> 
> * Baoquan He <bhe@redhat.com> wrote:
> 
> > ACPI MADT has a 32-bit field providing lapic address at which
> > each processor can access its lapic information. MADT also contains
> > an optional entry to provide a 64-bit address to override the 32-bit
> > one. However the current code does the lapic address override entry
> > parsing twice. One is in early_acpi_boot_init() because AMD NUMA need
> > get boot_cpu_id earlier. The other is in acpi_boot_init() which parses
> > all MADT entries.
> > 
> > So in this patch remove the repeated code in the 2nd part. Meanwhile
> > print lapic override entry information like other MADT entry, this
> > will be added to boot log.
> 
> it is not at all clear to me from this changelog whether the change is supposed to 
> change anything. If not then please spell it out explicitly:
> 
>   "This patch is not supposed to change any behavior."

I don't know if adding new information to boot log can be seen as
behavior change. If lapic override entry exist, the code change will
add one line of message to boot log:

	LAPIC_ADDR_OVR (address[0xXXXXXXXX])

If this is not behavior change, I will add the sentence you suggested.

Thanks
Baoquan

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