On 04/03/2025 10:47 pm, Stefano Stabellini wrote: > On Mon, 3 Mar 2025, Andrew Cooper wrote: >> When a watchdog fires, the domain is crashed and can't dump any state. >> >> Xen allows a domain to have two separate watchdogs. Therefore, for a >> domain running multiple watchdogs (e.g. one based around network, one >> for disk), it is important for diagnostics to know which watchdog >> fired. >> >> As the printk() is in a timer callback, this is a bit awkward to >> arrange, but there are 12 spare bits in the bottom of the domain >> pointer owing to its alignment. >> >> Reuse these bits to encode the watchdog id too, so the one which fired >> is identified when the domain is crashed. >> >> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> > The code looks like it would work as intended.
It's already deployed into production[1]. (Guess /why/ we need to distinguish the two watchdogs.) > I checked with the MISRA rules and it looks like it would fall under the > allowed exception. Please have a run through ECLAIR to make sure it > doesn't cause regressions (especially R11.2). Eclair is happy: https://gitlab.com/xen-project/people/andyhhp/xen/-/pipelines/1700050949 ~Andrew [1] Actually, the version that took me 2 minute to write one evening over beer after work when the initial request for help came in. Followed shortly by an explanation of how alignment works.
