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From: Michael Walle <michael@walle.cc>
To: u-boot@lists.denx.de
Subject: [PATCH 2/2] watchdog: add watchdog behavior configuration
Date: Thu, 24 Sep 2020 22:30:24 +0200	[thread overview]
Message-ID: <6907362452de14b4b642325cd0d4e3f9@walle.cc> (raw)
In-Reply-To: <20200924131931.GF14816@bill-the-cat>

Am 2020-09-24 15:19, schrieb Tom Rini:
> On Thu, Sep 24, 2020 at 09:33:50AM +0200, Michael Walle wrote:
>> Am 2020-09-23 19:35, schrieb Tom Rini:
[..]

>> > > Not printf(), maybe log_info().
>> > >
>> > > The disabling has to occur in ExitBootServices() (aka.
>> > > efi_exit_boot_services()). Here we are in the middle of an executing
>> > > UEFI application. Printing anything on the screen may mess up the
>> > > output
>> > > of the UEFI application.
>> > >
>> > > So, please, don't output anything.
>> >
>> > We need to find a good way to inform the user we're disabling their
>> > watchdog.  Maybe before we fully jump in to UEFI note that it will be
>> > disabled before entering the OS?  Or something a bit more generally
>> > understood than ExitBootServices() having been called.  I don't know
>> > _where_ the best place is, but I think it's important to inform the
>> > user.
>> 
>> The watchdog is only disabled in the "supervise u-boot" mode, why
>> would we need to inform the user? It was the users choice to have
>> the timer only enabled in u-boot.
>> 
>> Or do you mean if for example the vendor chooses that option and
>> in this case the user doesn't know anything about it? The mode
>> is indicated in the "WDT:" output.
> 
> I'm talking about the case where we say we've enabled the WDT to
> supervise OS, but then bootefi something and have disabled the watchdog
> (to meet UEFI requirements) but didn't tell the user we've turned off
> the WDT that we had told them is on.

Ah, do you really want to have a different behavior between bootm and
bootefi? Thats even more suprising IMHO.

I had the following in mind:

+config WATCHDOG_SUPERVISE_OS
+       bool "Supervise U-boot and operating system"
+       help
+         Upon U-Boot startup the first watchdog will be started 
automatically
+         and kept running even after booting the operating system.
+         Be aware, that the operating system needs to service the 
watchdog!
+
+         Additionally, this is not UEFI compliant because:
+          - the timeout won't be set to 5 minutes before starting the 
OS and
+          - the watchdog timer isn't stopped after the OS calls
+            ExitBootServices().

-michael

  reply	other threads:[~2020-09-24 20:30 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-23 16:45 [PATCH 1/2] watchdog: Hide WATCHDOG_RESET_DISABLE Michael Walle
2020-09-23 16:45 ` [PATCH 2/2] watchdog: add watchdog behavior configuration Michael Walle
2020-09-23 17:01   ` Mark Kettenis
2020-09-23 17:14     ` Tom Rini
2020-09-23 17:31       ` Heinrich Schuchardt
2020-09-23 17:35         ` Tom Rini
2020-09-24  7:33           ` Michael Walle
2020-09-24  8:10             ` Mark Kettenis
2020-09-24  8:20               ` Michael Walle
2020-09-24 10:22                 ` Mark Kettenis
2020-09-24 21:05                   ` Michael Walle
2020-09-24 13:19             ` Tom Rini
2020-09-24 20:30               ` Michael Walle [this message]
2020-09-24 20:58                 ` Mark Kettenis
2020-09-24 21:14                   ` Michael Walle
2020-09-25  1:17                     ` Tom Rini
2020-09-25  8:36               ` Wolfgang Denk
2020-09-25 11:29                 ` Heinrich Schuchardt
2020-09-25 13:00                   ` Tom Rini
2020-09-25 13:26                     ` Heinrich Schuchardt
2020-09-26  8:45                       ` Wolfgang Denk
2020-09-26 10:54                         ` Mark Kettenis
2020-09-26 12:39                           ` Heinrich Schuchardt
2020-09-26 12:44                             ` Tom Rini
2020-09-27 16:06                               ` Michael Walle
2020-09-28 15:34                                 ` Tom Rini
2020-09-26 14:40                             ` Wolfgang Denk
2020-09-26 14:22                           ` Wolfgang Denk
2020-09-25 13:04                   ` Wolfgang Denk
2020-10-04 14:55                     ` Michael Walle
2020-10-04 15:10                       ` Heinrich Schuchardt
2020-10-04 15:40                         ` Tom Rini
2020-09-23 17:53       ` Mark Kettenis
2020-09-23 18:51         ` Heinrich Schuchardt
2020-09-23 19:02           ` Tom Rini
2020-09-23 20:01             ` Heinrich Schuchardt
2020-09-23 20:23               ` Tom Rini
2020-09-23 20:58                 ` Heinrich Schuchardt
2020-09-23 21:09                   ` Tom Rini
2020-09-23 20:38           ` Michael Walle
2020-09-23 21:01             ` Heinrich Schuchardt
2020-09-23 17:21   ` Heinrich Schuchardt
2020-09-23 17:28     ` Tom Rini
2020-09-24  6:53       ` Michael Walle

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