On Tue, Jan 06, 2015 at 04:05:00PM +0800, Dave Young wrote: > On 01/05/15 at 08:54pm, Vivek Goyal wrote: > > On Tue, Jan 06, 2015 at 09:44:05AM +0800, Dave Young wrote: > > > On 01/02/15 at 08:17am, Vivek Goyal wrote: > > > > On Fri, Jan 02, 2015 at 08:07:20AM -0500, Prarit Bhargava wrote: > > > > > > > > > > > > > > > On 01/02/2015 07:54 AM, Vivek Goyal wrote: > > > > > > On Tue, Dec 30, 2014 at 09:57:51AM -0500, Prarit Bhargava wrote: > > > > > >> panic_on_warn kernel parameter will cause the kernel to panic when a > > > > > >> WARN() is hit in the kernel. This is not a good situation for the kdump > > > > > >> kernel because then it would be possible for the kdump kernel to panic in > > > > > >> a non-fatal WARN(). > > > > > >> > > > > > >> This patch removes panic_on_warn as a kernel parameter for the kdump > > > > > >> kernel. > > > > > >> > > > > > > > > > > > > I think modifying kexec-tools is not best place for this. It probably is better to take care of this in distribution specific scripts. > > > > > > > > > > > > In the past we have learnt that it is best that kexec-tools does least > > > > > > amount of manipulation with command line. > > > > > > > > > > Well .. here's the question to think about: what does adding panic_on_warn to > > > > > the kdump kernel get you? AFAICT, nothing. > > > > > > > > Let us consider a hypothetical situation. What if we have some buggy code > > > > which will corrupt file system in certain situation and we detect that > > > > situation and throw a warning. > > > > > > > > In that case as a work around specifying panic_on_warn in kdump kernel > > > > will make sense as we don't want to make further progress if we hit > > > > the warning as it has potential to corrupt fs. > > > > > > > > Again this is hypothetical but it can happen. So panic_on_warn might > > > > still be useful in kdump kernel for some corner debugging cases. > > > > > > > > That's why I think we should do it in distribution specific scripts > > > > and that too only if user did not specify panic_on_warn for second > > > > kernel explicitly. > > > > > > Thinking of user who use upstream kexec-tools instead of distribution toolset, > > > In case kexec --reuse-cmdline, it will copy /proc/cmdline, but user will have > > > no way to remove part of them. > > > > > > I do want to insist on removing 'panic_on_warn' in upstream kexec-tools, but > > > we should give user an option to remove it. Something like: > > > > > > kexec --reuse-cmdline --remove-params="panic_on_warn" will be good. > > > > If user is using --reuse-commandline at the same time does not want some > > of the parameters from command line, then don't use --reuse-commandline. > > > > This is overenginnering. First provide an option to reuse the commandline > > and provide another option to selectively remove some parameters from that > > commandline. > > > > What's wrong with existing parameters of --command-line. This just allows > > user to specify whatever command line is suitable. > > > > So, no, we should not provide --remove-params. If existing command line > > does not work for new kenrel, then user should not use > > --reuse-commandline option. > > Hmm, ok. So hope one who is use panic_on_warn in 1st kernel know what he is doing > and do not simply copy the 1st kernel cmdline for 2nd kernel. --reuse-commandline will work only for kexec case and not kdump case. And in case of kexec, it is fine to use panic_on_warn in kexeced kernel. So there is no need to worry here. Thanks Vivek
