x86, setup: guard against pre-ACPI 3 e820 code not updating %ecx
Impact: BIOS bug safety
For pre-ACPI 3 BIOSes, pre-initialize the end of the e820 buffer just
in case the BIOS returns an unchanged %ecx but without actually
touching the ACPI 3 extended flags field.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c
index d5d2360..5054c2d 100644
--- a/arch/x86/boot/memory.c
+++ b/arch/x86/boot/memory.c
@@ -31,6 +31,12 @@
struct e820entry *desc = boot_params.e820_map;
static struct e820_ext_entry buf; /* static so it is zeroed */
+ /*
+ * Set this here so that if the BIOS doesn't change this field
+ * but still doesn't change %ecx, we're still okay...
+ */
+ buf.ext_flags = 1;
+
do {
size = sizeof buf;