Starting with d9a0c9413e81d3c0affc6383693bdd28dc863a5c, GRUB unconditionally disables watchdog on EFI platforms. This opens up a window (starting at GRUB's grub_efi_init(), until OS re-enables it) when EFI system operates w/o watchdog. If an EFI system gets stuck in that window, the chipset will never reset the system.
Remove the unconditional disablement of the watchdog, and create a command line
interface to enable/disable watchdog:
efi-watchdog (enable|disable) <timeout>
---
docs/grub.texi | 8 ++++++
grub-core/kern/efi/init.c | 60 ++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 65 insertions(+), 3 deletions(-)
diff --git a/docs/grub.texi b/docs/grub.texi
index b9f41a7..4cfd50c 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -3784,6 +3784,7 @@ you forget a command, you can run the command
@command{help}
* distrust:: Remove a pubkey from trusted keys
* drivemap:: Map a drive to another
* echo:: Display a line of text
+* efi-watchdog:: Manipulate EFI watchdog
* eval:: Evaluate agruments as GRUB commands
* export:: Export an environment variable
* false:: Do nothing, unsuccessfully
@@ -4192,6 +4193,13 @@ When interpreting backslash escapes, backslash followed
by any other
character will print that character.
@end deffn
+@node efi-watchdog
+@subsection efi-watchdog
+
+@deffn Command efi-watchdog enable|disable <timeout>
+Enable or disable the system's watchdog timer. Only available in EFI targeted
+GRUB.
+@end deffn
@node eval
@subsection eval
diff --git a/grub-core/kern/efi/init.c b/grub-core/kern/efi/init.c
index e9c85de..f8a79eb 100644
--- a/grub-core/kern/efi/init.c
+++ b/grub-core/kern/efi/init.c
@@ -25,9 +25,62 @@
#include <grub/env.h>
#include <grub/mm.h>
#include <grub/kernel.h>
+#include <grub/extcmd.h>
+#include <grub/command.h>
grub_addr_t grub_modbase;
+static grub_command_t cmd_list;
+
+static grub_err_t
+grub_cmd_efi_watchdog (grub_command_t cmd __attribute__ ((unused)),
+ int argc, char **args)
+{
+ long input;
+ grub_efi_status_t status;
+ grub_efi_uintn_t timeout;
+
+ if (argc < 1)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ N_("efi-watchdog (enable|disable) <timeout>"));
+
+ if (grub_strcasecmp (args[0], "enable") == 0) {
+
+ if (argc != 2)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ N_("efi-watchdog enable <timeout>"));
+
+ input = grub_strtol (args[1], 0, 0);
+
+ if (input >= 0) {
+ timeout = input;
+ } else {
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ N_("<timeout> must be non-negative"));
+ }
+
+ } else if (grub_strcasecmp (args[0], "disable") == 0) {
+
+ if (argc != 1)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ N_("efi-watchdog disable"));
+ timeout = 0;
+
+ } else {
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ N_("efi-watchdog (enable|disable) <timeout>"));
+ }
+
+ status = efi_call_4
(grub_efi_system_table->boot_services->set_watchdog_timer,
+ timeout, 0, sizeof(L"GRUB"), L"GRUB");
+
+ if (status != GRUB_EFI_SUCCESS)
+ return grub_error (GRUB_ERR_BUG,
+ N_("EFI SetWatchdogTimer() bug"));
+ else
+ return GRUB_ERR_NONE;
+}
+
void
grub_efi_init (void)
{
@@ -39,10 +92,10 @@ grub_efi_init (void)
/* Initialize the memory management system. */
grub_efi_mm_init ();
- efi_call_4 (grub_efi_system_table->boot_services->set_watchdog_timer,
- 0, 0, 0, NULL);
-
grub_efidisk_init ();
+
+ cmd_list = grub_register_command ("efi-watchdog", grub_cmd_efi_watchdog, 0,
+ N_("Enable/Disable system's watchdog
timer."));
}
void (*grub_efi_net_config) (grub_efi_handle_t hnd,
@@ -77,4 +130,5 @@ grub_efi_fini (void)
{
grub_efidisk_fini ();
grub_console_fini ();
+ grub_unregister_command (cmd_list);
}
--
1.7.9.5
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