On Thu, Dec 2, 2021, at 06:14, Hector Martin wrote: > On 14/11/2021 22.18, Alyssa Rosenzweig wrote: >>>>> + * This HW block has three separate watchdogs. WD0 resets the machine >>>>> + * to recovery mode and is not very useful for us. WD1 and WD2 trigger a normal >>>>> + * machine reset. WD0 additionally supports a configurable interrupt. >>>> >>>> Do we have any idea what the difference between WD1 and WD2 is? >>> >>> I've never seen macOS write to WD2 when running in our hypervisor and only >>> found that one when I was looking at the rest of the MMIO region. >>> >From what I can tell it works exactly like WD1. >> >> Makes sense, thanks. >> > > Are any of these watchdogs active when we boot, and are we leaving them > like that? I'm pretty sure at least some of the coprocessors have their > own watchdog (SMC...), which might be one of these. We should make sure > we don't clobber that. That's what I thought at first as well but they are all disabled except for WD1 which we disable in m1n1. I don't touch WD0 or WD2 in this driver anyway and v2 also checks if WD1 is running (because it might've been started by u-boot) and makes sure the watchdog core is aware and keeps pinging it. Sven
