[U-Boot] [PATCH 06/11] efi_loader: implement SetWatchdogTimer

Heinrich Schuchardt xypron.glpk at gmx.de
Mon Oct 9 06:05:13 UTC 2017


On 10/09/2017 06:42 AM, Alexander Graf wrote:
> 
> 
> On 08.10.17 06:57, Heinrich Schuchardt wrote:
>> The watchdog is initialized with a 5 minute timeout period.
>> It can be reset by SetWatchdogTimer.
>> It is stopped by ExitBoottimeServices.
>>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>> ---
>>  cmd/bootefi.c                 |  1 +
>>  include/efi_loader.h          |  4 +++
>>  lib/efi_loader/Makefile       |  2 +-
>>  lib/efi_loader/efi_boottime.c | 15 ++---------
>>  lib/efi_loader/efi_watchdog.c | 59 +++++++++++++++++++++++++++++++++++++++++++
>>  5 files changed, 67 insertions(+), 14 deletions(-)
>>  create mode 100644 lib/efi_loader/efi_watchdog.c
>>
>> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
>> index b7087e3da8..24958ada46 100644
>> --- a/cmd/bootefi.c
>> +++ b/cmd/bootefi.c
>> @@ -43,6 +43,7 @@ static void efi_init_obj_list(void)
>>  #ifdef CONFIG_GENERATE_SMBIOS_TABLE
>>  	efi_smbios_register();
>>  #endif
>> +	efi_watchdog_register();
>>  
>>  	/* Initialize EFI runtime services */
>>  	efi_reset_system_init();
>> diff --git a/include/efi_loader.h b/include/efi_loader.h
>> index e1179b7dcd..223d8d8222 100644
>> --- a/include/efi_loader.h
>> +++ b/include/efi_loader.h
>> @@ -163,6 +163,8 @@ int efi_disk_register(void);
>>  int efi_gop_register(void);
>>  /* Called by bootefi to make the network interface available */
>>  int efi_net_register(void);
>> +/* Called by bootefi to make the watchdog available */
>> +int efi_watchdog_register(void);
>>  /* Called by bootefi to make SMBIOS tables available */
>>  void efi_smbios_register(void);
>>  
>> @@ -171,6 +173,8 @@ efi_fs_from_path(struct efi_device_path *fp);
>>  
>>  /* Called by networking code to memorize the dhcp ack package */
>>  void efi_net_set_dhcp_ack(void *pkt, int len);
>> +/* Called by efi_set_watchdog_timer to reset the timer */
>> +efi_status_t efi_set_watchdog(unsigned long timeout);
>>  
>>  /* Called from places to check whether a timer expired */
>>  void efi_timer_check(void);
>> diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
>> index ddb978f650..83d879b686 100644
>> --- a/lib/efi_loader/Makefile
>> +++ b/lib/efi_loader/Makefile
>> @@ -17,7 +17,7 @@ endif
>>  obj-$(CONFIG_CMD_BOOTEFI_HELLO) += helloworld_efi.o
>>  obj-y += efi_image_loader.o efi_boottime.o efi_runtime.o efi_console.o
>>  obj-y += efi_memory.o efi_device_path_to_text.o efi_device_path.o
>> -obj-y += efi_file.o efi_variable.o efi_bootmgr.o
>> +obj-y += efi_file.o efi_variable.o efi_bootmgr.o efi_watchdog.o
>>  obj-$(CONFIG_LCD) += efi_gop.o
>>  obj-$(CONFIG_DM_VIDEO) += efi_gop.o
>>  obj-$(CONFIG_PARTITIONS) += efi_disk.o
>> diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
>> index 30577f717e..81e7d818fc 100644
>> --- a/lib/efi_loader/efi_boottime.c
>> +++ b/lib/efi_loader/efi_boottime.c
>> @@ -155,18 +155,6 @@ void efi_signal_event(struct efi_event *event)
>>  	event->is_queued = false;
>>  }
>>  
>> -/*
>> - * Write a debug message for an EPI API service that is not implemented yet.
>> - *
>> - * @funcname	function that is not yet implemented
>> - * @return	EFI_UNSUPPORTED
>> - */
>> -static efi_status_t efi_unsupported(const char *funcname)
>> -{
>> -	debug("EFI: App called into unimplemented function %s\n", funcname);
>> -	return EFI_EXIT(EFI_UNSUPPORTED);
>> -}
>> -
>>  /*
>>   * Raise the task priority level.
>>   *
>> @@ -1454,6 +1442,7 @@ static efi_status_t EFIAPI efi_exit_boot_services(void *image_handle,
>>  	bootm_disable_interrupts();
>>  
>>  	/* Give the payload some time to boot */
>> +	efi_set_watchdog(0);
>>  	WATCHDOG_RESET();
>>  
>>  	return EFI_EXIT(EFI_SUCCESS);
>> @@ -1514,7 +1503,7 @@ static efi_status_t EFIAPI efi_set_watchdog_timer(unsigned long timeout,
>>  {
>>  	EFI_ENTRY("%ld, 0x%"PRIx64", %ld, %p", timeout, watchdog_code,
>>  		  data_size, watchdog_data);
>> -	return efi_unsupported(__func__);
>> +	return EFI_EXIT(efi_set_watchdog(timeout));
>>  }
>>  
>>  /*
>> diff --git a/lib/efi_loader/efi_watchdog.c b/lib/efi_loader/efi_watchdog.c
>> new file mode 100644
>> index 0000000000..50e95290ea
>> --- /dev/null
>> +++ b/lib/efi_loader/efi_watchdog.c
>> @@ -0,0 +1,59 @@
>> +/*
>> + *  EFI device path interface
> 
> Not quite I guess?
> 
>> + *
>> + *  Copyright (c) 2017 Heinrich Schuchardt
>> + *
>> + *  SPDX-License-Identifier:     GPL-2.0+
>> + */
>> +
>> +#include <common.h>
>> +#include <efi_loader.h>
>> +
>> +static struct efi_event *watchdog_timer_event;
>> +
>> +static void EFIAPI efi_watchdog_timer_notify(struct efi_event *event,
>> +					     void *context)
>> +{
>> +	EFI_ENTRY("%p, %p", event, context);
>> +
>> +	printf("\nEFI: Watchdog timeout\n");
>> +	EFI_CALL_VOID(efi_runtime_services.reset_system(EFI_RESET_COLD,
>> +							EFI_SUCCESS, 0, NULL));
>> +
>> +	EFI_EXIT(EFI_UNSUPPORTED);
>> +}
>> +
>> +efi_status_t efi_set_watchdog(unsigned long timeout)
>> +{
>> +	efi_status_t r;
>> +
>> +	if (timeout)
>> +		/* Reset watchdog */
>> +		r = efi_set_timer(watchdog_timer_event, EFI_TIMER_RELATIVE,
>> +				  10000000 * timeout);
>> +	else
>> +		/* Deactivate watchdog */
>> +		r = efi_set_timer(watchdog_timer_event, EFI_TIMER_STOP, 0);
>> +	return r;
>> +}
>> +
>> +/* This gets called from do_bootefi_exec(). */
>> +int efi_watchdog_register(void)
>> +{
>> +	efi_status_t r;
>> +
>> +	r = efi_create_event(EVT_TIMER | EVT_NOTIFY_SIGNAL, TPL_CALLBACK,
>> +			     efi_watchdog_timer_notify, NULL,
>> +			     &watchdog_timer_event);
> 
> How useful is a timer based watchdog without proper timer implementation?
> 

Do we have boards where the timer does not work?
On these we would have problems with EFI applications.

> Is there a specific case where you needed it working?

Both EFI shell and iPXE reset the timer.

> 
> Also, is there a good reason not to use the hardware watchdog when it's
> available?
How can I detect that the hardware watchdog is usable?
Can I set hardware watchdogs to arbitrary timeouts?
We need the EFI timer to be working anyway for many applications.

> 
>> +	if (r != EFI_SUCCESS) {
>> +		printf("ERROR: Failed to register watchdog event\n");
>> +		return r;
>> +	}
>> +	/* Set watchdog to trigger after 5 minutes */
>> +	r = efi_set_watchdog(300);
> 
> Is this expected somewhere? Does the spec mention default watchdog timeouts?

UEFI Spec 2.7 Erratum A:

<cite>The watchdog must be set to  a period of 5 minutes. The EFI
Image may reset or disable the watchdog timer as needed. If control
is returned to the firmware's boot manager, the watchdog timer must
be disabled.</cite>

Regards

Heinrich

> 
> 
> Alex
> 
>> +	if (r != EFI_SUCCESS) {
>> +		printf("ERROR: Failed to set watchdog timer\n");
>> +		return r;
>> +	}
>> +	return 0;
>> +}
>>
> 



More information about the U-Boot mailing list