[PATCH, v2] x86: don't allocate dummy page for wrong madt/mptable

From: Yinghai Lu
Date: Wed May 20 2009 - 14:35:34 EST



in io_apic_init_mapping, if nr_ioapics > 0, we don't need to check
smp_found_config further.

also don't need to allocate dummy pages if we got wrong mptable/madt.
like bad ioapic address. because skip_ioapic_setup already guard that
later.

[ Impact: save 4k when bad mptable/madt or skip_ioapic_setup ]

Sign-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
---
arch/x86/kernel/apic/io_apic.c | 48 +++++++++++++++++++++--------------------
1 file changed, 25 insertions(+), 23 deletions(-)

Index: linux-2.6/arch/x86/kernel/apic/io_apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/io_apic.c
+++ linux-2.6/arch/x86/kernel/apic/io_apic.c
@@ -1887,7 +1887,9 @@ __apicdebuginit(int) print_all_ICs(void)
return 0;

print_all_local_APICs();
- print_IO_APIC();
+
+ if (!skip_ioapic_setup && nr_ioapics)
+ print_IO_APIC();

return 0;
}
@@ -3828,6 +3830,9 @@ void __init probe_nr_irqs_gsi(void)
{
int nr = 0;

+ if (skip_ioapic_setup)
+ return;
+
nr = acpi_probe_gsi();
if (nr > nr_irqs_gsi) {
nr_irqs_gsi = nr;
@@ -4139,29 +4144,26 @@ void __init ioapic_init_mappings(void)
struct resource *ioapic_res;
int i;

- ioapic_res = ioapic_setup_resources();
+ if (nr_ioapics < 1 || skip_ioapic_setup)
+ return;
+
for (i = 0; i < nr_ioapics; i++) {
- if (smp_found_config) {
- ioapic_phys = mp_ioapics[i].apicaddr;
-#ifdef CONFIG_X86_32
- if (!ioapic_phys) {
- printk(KERN_ERR
- "WARNING: bogus zero IO-APIC "
- "address found in MPTABLE, "
- "disabling IO/APIC support!\n");
- smp_found_config = 0;
- skip_ioapic_setup = 1;
- goto fake_ioapic_page;
- }
-#endif
- } else {
-#ifdef CONFIG_X86_32
-fake_ioapic_page:
-#endif
- ioapic_phys = (unsigned long)
- alloc_bootmem_pages(PAGE_SIZE);
- ioapic_phys = __pa(ioapic_phys);
+ ioapic_phys = mp_ioapics[i].apicaddr;
+ if (!ioapic_phys) {
+ printk(KERN_ERR
+ "WARNING: bogus zero IO-APIC "
+ "address found in MPTABLE or MADT, "
+ "disabling IO/APIC support!\n");
+ smp_found_config = 0;
+ skip_ioapic_setup = 1;
+ return;
}
+ }
+
+ ioapic_res = ioapic_setup_resources();
+ for (i = 0; i < nr_ioapics; i++) {
+ ioapic_phys = mp_ioapics[i].apicaddr;
+
set_fixmap_nocache(idx, ioapic_phys);
apic_printk(APIC_VERBOSE,
"mapped IOAPIC to %08lx (%08lx)\n",
@@ -4182,7 +4184,7 @@ static int __init ioapic_insert_resource
struct resource *r = ioapic_resources;

if (!r) {
- if (nr_ioapics > 0) {
+ if (nr_ioapics > 0 && !skip_ioapic_setup) {
printk(KERN_ERR
"IO APIC resources couldn't be allocated.\n");
return -1;
--
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