summaryrefslogtreecommitdiff
path: root/arch/x86/include/asm/highmem.h
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/include/asm/highmem.h')
-rw-r--r--arch/x86/include/asm/highmem.h25
1 files changed, 14 insertions, 11 deletions
diff --git a/arch/x86/include/asm/highmem.h b/arch/x86/include/asm/highmem.h
index 302a323b3f67..04e9d023168f 100644
--- a/arch/x86/include/asm/highmem.h
+++ b/arch/x86/include/asm/highmem.h
@@ -38,17 +38,20 @@ extern unsigned long highstart_pfn, highend_pfn;
/*
* Ordering is:
*
- * FIXADDR_TOP
- * fixed_addresses
- * FIXADDR_START
- * temp fixed addresses
- * FIXADDR_BOOT_START
- * Persistent kmap area
- * PKMAP_BASE
- * VMALLOC_END
- * Vmalloc area
- * VMALLOC_START
- * high_memory
+ * high memory on: high_memory off:
+ * FIXADDR_TOP FIXADDR_TOP
+ * fixed addresses fixed addresses
+ * FIXADDR_START FIXADDR_START
+ * temp fixed addresses/persistent kmap area VMALLOC_END
+ * PKMAP_BASE temp fixed addresses/vmalloc area
+ * VMALLOC_END VMALLOC_START
+ * vmalloc area high_memory
+ * VMALLOC_START
+ * high_memory
+ *
+ * The temp fixed area is only used during boot for early_ioremap(), and
+ * it is unused when the ioremap() is functional. vmalloc/pkmap area become
+ * available after early boot so the temp fixed area is available for re-use.
*/
#define LAST_PKMAP_MASK (LAST_PKMAP-1)
#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)