Hi David, On 05/10/21 at 01:01pm, David Hildenbrand wrote: [snip] > It also bugged me for quite a bit that we don't have a sane way to achieve > what we're doing here upstream. It somewhat feels like "this doesn't belong > in the kernel and is user policy" but then, the existing kernel support is > suboptimal. > > Maybe reserving some "maybe too big but okayish to boot the system in a sane > environment -- e.g., X% of system RAM and at least Y" size first and > shrinking it later as triggered by user space early (where we do seem to > have a way to pre-calculate things now) might actually be a good direction > to look into. Hmm, that is also an option we considered before. Even for your suggestion we still need a kernel option to set the default ratio/value. and the ratio/value should be another patch which expands crashkernel syntax. Actually the kconfig help text in this patch is indeed misleading, it is not introducing crashkernel=a:b... and no need to explain about the crashkernel syntax, the config option is actually just some interface we can add any valid crashkernel settings to be used by default. So current patch help text describes the default value of crash auto str, instead of describes what crash auto str is. And crashkernel=auto makes this more flexibly. We can tune the values easily when upgrading. But if we pass a fixed value in userspace we can not know if the value is set by distribution automatically or by user manually thus we can not blindly update it. Thanks Dave
