Add a more verbose comment to explain why set_virtual_address_map is
replaced why a dummy function
Signed-Off-By: Simon Horman <[EMAIL PROTECTED]>
Index: kexec-tools-patch-boot-params/purgatory/arch/ia64/purgatory-ia64.c
===================================================================
--- kexec-tools-patch-boot-params.orig/purgatory/arch/ia64/purgatory-ia64.c
2006-09-20 16:17:34.000000000 +0900
+++ kexec-tools-patch-boot-params/purgatory/arch/ia64/purgatory-ia64.c
2006-09-20 16:27:24.000000000 +0900
@@ -241,7 +241,22 @@
struct ia64_boot_param *new_boot_param =
(struct ia64_boot_param *) params->boot_param_base;
memcpy(new_boot_param, boot_param, 4096);
- /* patch efi_runtime->set_virtual_address_map to a dummy function */
+
+ /*
+ * patch efi_runtime->set_virtual_address_map to a dummy function
+ *
+ * The EFI specification mandates that set_virtual_address_map only
+ * takes effect the first time that it is called, and that
+ * subsequent calls will return error. By replacing it with a
+ * dummy function the new OS can think it is calling it again
+ * without either the OS or any buggy EFI implementations getting
+ * upset.
+ *
+ * Note: as the EFI specification says that set_virtual_address_map
+ * will only take affect the first time it is called, the mapping
+ * can't be updated, and thus mapping of the old and new OS really
+ * needs to be the same.
+ */
len = __dummy_efi_function_end - __dummy_efi_function;
memcpy(command_line + command_line_len,
__dummy_efi_function, len);
--
--
Horms
H: http://www.vergenet.net/~horms/
W: http://www.valinux.co.jp/en/
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