On 7/11/24 15:14, James Hilliard wrote:
On Thu, Jul 11, 2024 at 3:42 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
On 7/11/24 14:09, James Hilliard wrote:
The best we could possibly do might be to add a check for the bit in register
0xf1 and warn the user that they might have to use the ACPI driver if the bit
is set. I am not sure if that would be helpful or just add noise, though.
Do your systems which work with the it87_wdt driver have that 0xF1 bit not set?
I only have one such system left, and the bit is not set on that system.
I avoid buying hardware with ITE Super-IO chips nowadays since their support
for Linux is non-existent.
Yeah, I got stuck with a fleet of these boards, trying to make the best of it.
I'm thinking we should check for that bit and prevent loading the
it87_wdt driver if
No. That would create the risk of no longer loading the driver on systems where
it currently works.
Hmm, any idea how likely it would be that the bit could be set on a board
which the driver works on?
No idea, but I would not want to disable it just to find out with a flurry
of angry e-mails.
Or maybe best to have a quirks table with dmi matching to disable the
driver on known broken systems?
it's set(maybe along with an override param). That way the wdat_wdt driver I
I prefer the less invasive version of logging a message. The user can then
block the it87_wdt driver if it doesn't work.
Hmm, I build multiple watchdog drivers into the same kernel and somewhat
rely on the autodetection working correctly as I support multiple boards
with the same kernel build. It's not exactly trivial to conditionally prevent
drivers from loading when built into the kernel AFAIU.
Those drivers should never be built into the kernel; they should be built
as modules, and module load instructions in /etc/modprobe.d (or whatever the
distribution uses) should be used to determine which drivers to load. I really
would not want to rely on a bit such as the smi interrupt bit to determine
if the watchdog is used by ACPI.
This is actually a multi-level problem: Even if there is an ACPI watchdog,
that does not mean that ACPI uses the Super-IO chip for its watchdog implementation.
It might as well using the ICH watchdog on Intel systems or the TCO watchdog on
AMD systems. Similar, even if the SMI interrupt bit is not set, it is essentially
unknown if the it87_wdt driver actually works, because its reset pins might not
be connected. Or, of course, both watchdogs might work.
Assuming the wdat_wdt driver auto-loads on your system (I think it should),
can you write a little script which loads the it87_wdt driver only if the
wdat_wdt driver is not loaded ?
Actually, just building the wdat_wdt driver into the kernel and it87_wdt as
module (and loading it via modules.d) should work since the wdat_wdt driver
would then be instantiated first, and the first watchdog is all that systemd
cares about.
Thanks,
Guenter
