On Tue, Mar 21, 2017 at 11:48:02AM +0800, Fu Wei wrote:

Hi Mark, Lurndal,

quoted

quoted

      The base server system implements _a_ Generic Watchdog as
      specified in APPENDIX A: Generic Watchdog.

  It is a requirement of a conforming implementation that there
be a generic watchdog (impl as per the appendix).   That doesn't preclude
an implmentation from providing additional watchdogs (for example, if
the processor implements EL3, it is likely that an implementation
will include a secure watchdog as well as a non-secure watchdog).

  The SBSA describes the minimal hardware requirements for a
compliant server.

So I think, for the SBSA watchdog:

(1) there maybe more then one non-secure watchdog in GTDT

I suppose a firmware vendor could chose to expose more than the
platform minimum to linux.   Not quite sure what linux would
do with it :-)

(2) we may also need to skip  secure watchdogs in GTDT,
and only register non-secure watchdogs into platform resources.

The secure watchdog will, be definition, never be accessible
to non-secure EL2 or non-secure EL1, so only in the case of
a secure EL1 operating system would the secure watchdog ever
be conveyed through ACPI.   I don't think secure EL1 is in
the scope of the SBSA, or something that needs to be accomodated
in the GTDT at this time.

scott