diff options
| -rw-r--r-- | purgatory/arch/ia64/purgatory-ia64.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/purgatory/arch/ia64/purgatory-ia64.c b/purgatory/arch/ia64/purgatory-ia64.c index 661ab32..312cdcc 100644 --- a/purgatory/arch/ia64/purgatory-ia64.c +++ b/purgatory/arch/ia64/purgatory-ia64.c @@ -240,7 +240,22 @@ ia64_env_setup(struct ia64_boot_param *boot_param, 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); |