On Thu 2020-08-13 10:55:00, Sergey Senozhatsky wrote: > On (20/08/11 15:02), Petr Mladek wrote: > > On Tue 2020-08-11 14:05:12, Thomas Gleixner wrote: > > > Petr Mladek <pmladek@xxxxxxxx> writes: > > > > At least "crash" tool would need an update anyway. AFAIK, it checks > > > > the size of struct printk_log and refuses to read it when it changes. > > > > > > > > It means that the hack with VMCOREINFO_FIELD_OFFSET probably is not > > > > needed because we would need to update the crashdump-related tools anyway. > > > > > > > > Well, the timing is good. We are about to switch the printk ring > > > > buffer into a lockless one. It requires updating the crashdump tools > > > > as well. We could do this at the same time. The lockless ring buffer > > > > already is in linux-next. It is aimed for 5.10 or 5.11. > > > ... > > > > It would be great to synchronize all these changes changes of the > > > > printk log buffer structures. > > > > > > I agree that having one update is a good thing, but pretty please can we > > > finally make progress with this and not create yet another dependency? > > > > To make it clear. I definitely do not want to block lockless printk by > > this. > > > > BTW: I am not 100% convinced that storing all three timestamps is > > worth it. It increases the code complexity, metadata size. It needs > > an interface with the userspace that has to stay backward compatible. > > Can we, perhaps, store those various "alternative" timestamps in dict so > then whoever wants to read them can just parse the dict key:value pairs > attach to each printk message? Interesting idea. It might be a way how to add optional metadata without breaking compatibility with crashdump tools. Well, I have bad feeling about it. Some of the reasons might be: + would take more space (prefix + text vs. binary representation) + not reliable because dict is currently dropped when no space + it would make the controversial dictionary feature more important I would prefer to solve this by storing the timestamps in the structure with metadata. Best Regards, Petr _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
