when comparing the e820 direct from BIOS, and the one by kexec
BIOS-provided physical RAM map:
- BIOS-e820: 0000000000000000 - 0000000000097400 (usable)
+ BIOS-e820: 0000000000000100 - 0000000000097400 (usable)
BIOS-e820: 0000000000097400 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000e6000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 00000000dffa0000 (usable)
- BIOS-e820: 00000000dffae000 - 00000000dffb0000 type 9
+ BIOS-e820: 00000000dffae000 - 00000000dffb0000 (reserved)
BIOS-e820: 00000000dffb0000 - 00000000dffbe000 (ACPI data)
BIOS-e820: 00000000dffbe000 - 00000000dfff0000 (ACPI NVS)
BIOS-e820: 00000000dfff0000 - 00000000e0000000 (reserved)
BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
- BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved) =======> that is local apic address... somewhere we lost it
BIOS-e820: 00000000ff700000 - 0000000100000000 (reserved)
BIOS-e820: 0000000100000000 - 0000004020000000 (usable)
found one entry about reserved is missing for the kernel by kexec.
it turns out init_apic_mappings is called before e820_reserve_resources
in setup_arch. but e820_reserve_resources is using request_resource.
it will not handle the conflicts.
there are three ways to fix it
1. change request_resource in e820_reserve_resources to to insert_resource
2. move init_apic_mappings after e820_reserve_resources
3. use late_initcall to insert lapic resource.
this patch is using method 3, that is less intrusive.
in later version could consider to use method 1.
before patch
fed20000-ffffffff : PCI Bus #00
fee00000-fee00fff : Local APIC
fefff000-feffffff : pnp 00:09
ff700000-ffffffff : reserved
with patch will get map in first kernel
fed20000-ffffffff : PCI Bus #00
fee00000-fee00fff : Local APIC
fee00000-fee00fff : reserved
fefff000-feffffff : pnp 00:09
ff700000-ffffffff : reserved
Signed-off-by: Yinghai Lu <[email protected]>
diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index 5bdf1bc..cc6dd37 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -905,11 +905,6 @@ void __init init_apic_mappings(void)
apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
APIC_BASE, apic_phys);
- /* Put local APIC into the resource map. */
- lapic_resource.start = apic_phys;
- lapic_resource.end = lapic_resource.start + PAGE_SIZE - 1;
- insert_resource(&iomem_resource, &lapic_resource);
-
/*
* Fetch the APIC ID of the BSP in case we have a
* default configuration (or the MP table is broken).
@@ -1317,3 +1312,21 @@ static __init int setup_apicpmtimer(char *s)
}
__setup("apicpmtimer", setup_apicpmtimer);
+static int __init lapic_insert_resource(void)
+{
+ if (!apic_phys)
+ return -1;
+
+ /* Put local APIC into the resource map. */
+ lapic_resource.start = apic_phys;
+ lapic_resource.end = lapic_resource.start + PAGE_SIZE - 1;
+ insert_resource(&iomem_resource, &lapic_resource);
+
+ return 0;
+}
+
+/*
+ * need call insert after e820_reserve_resources()
+ * that is using request_resource
+ */
+late_initcall(lapic_insert_resource);
* Yinghai Lu <[email protected]> wrote:
> BIOS-e820: 00000000dfff0000 - 00000000e0000000 (reserved)
> BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
> - BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved) =======> that is local apic address... somewhere we lost it
> BIOS-e820: 00000000ff700000 - 0000000100000000 (reserved)
> BIOS-e820: 0000000100000000 - 0000004020000000 (usable)
>
> found one entry about reserved is missing for the kernel by kexec.
> +static int __init lapic_insert_resource(void)
thanks Yinghai, applied.
Ingo