On 02/06/2020 16.53, Stefan Roese wrote: > On 02.06.20 15:29, Rasmus Villemoes wrote: >> On 16/03/2020 16.52, Rasmus Villemoes wrote: >>> On 14/03/2020 13.04, Stefan Roese wrote: >>>> On 13.03.20 17:04, Rasmus Villemoes wrote: >>> >>>>> That at least solves half my problems and >>>>> might be useful to others as well. Then I'll have to figure out the >>>>> time-stands-still problem in some other way. >>>> >>>> If its too hard to enable interrupts in SPL for you or to provide some >>>> other means of a working get_timer() API, then we needto find another >>>> solution. You started with this weak function, which of course works. >>>> What other options are there? Adding a callback mechanism to register >>>> platform specific callback functions? Even though this might get a >>>> little bit too complicated. >>> >>> Now that I dig a bit more into this, I seem to remember that we actually >>> also had problems in U-Boot proper when loading a compressed kernel, so >>> for now we're using an uncompressed kernel in our FIT images. I will >>> have to re-investigate, but it now occurs to me that it might be due to >>> the fact that interrupts get disabled during bootm (which makes sense, >>> the same reason I stated previously of interrupt vectors about to be >>> overwritten), so even in U-Boot proper, time as measured by get_timer() >>> ceases to pass after that point, so all the WATCHDOG_RESET() calls from >>> the inflate code effectively get ignored. >>> >>> So it may be necessary to have some wdt_ratelimit_disable() hook that >>> can be called from bootm_disable_interrupts() and e.g. some >>> board-specific SPL code. I'll do some experiments and figure out if I do >>> indeed need such a hook. >> >> OK, I have now had time to do some more experiments. I have enabled the >> timer tick in SPL, so get_timer() now "normally" works. Together with >> the .dts based read of the hardware margin, that makes the watchdog >> handling mostly work. >> >> But, as I suspected, I do have a problem when loading a compressed >> kernel image - what I write above "so even in U-Boot proper, time as >> measured by get_timer() ceases to pass after that point, so all the >> WATCHDOG_RESET() calls from the inflate code effectively get ignored." >> is indeed the case. >> >> So, what's the best way to proceed? Should there be a hook disabling the >> rate-limiting logic that bootm_disable_interrupts() can call? Or must >> get_timer() always return a sensible result even with interrupts >> disabled? > > Wouldn't it make sense to move the bootm_disable_interrupts() call to > after loading and uncompressing the OS image? To right before jumping > to the OS?
No, because the point of disabling interrupts is that we may start writing to physical address 0 (e.g. if that's the load= address in the FIT image), which is also where the interrupt vectors reside - i.e., we're about to overwrite 0x900 (the decrementer interrupt vector), so if we don't disable interrupts, we'll crash on the very next decrementer interrupt (i.e., within one millisecond). Rasmus
