On Mon, Oct 19, 2015 at 04:22:46PM +0800, Dave Young wrote: > Hi, Simon > > On 10/16/15 at 10:33am, Simon Horman wrote: > > Hi Dave, > > > > On Fri, Oct 09, 2015 at 01:57:22PM +0800, Dave Young wrote: > > > Jan Stodola <jstodola at redhat.com> reported ppc64 root= is always added in kexec > > > kernel cmdline. But sometimes we need boot without root= for example we use > > > kexec to boot into installation initramfs image like below: > > > kexec --load vmlinuz --initrd=initrd.img --command-line=\ > > > "inst.repo=http://<server>/<path>/Server/ppc64le/os/" > > > > > > While creating dtb, in case there's no root= in user provided cmdline params > > > kexec-tools will find the original root= param used in 1st kernel and pass it > > > to 2nd kernel. This caused that user have no way to remove root= cmdline. > > > > > > Dropping that part of code so that one can get chance to kexec into 2nd kernel > > > without root= param. One can still provide root= in --command-line="" > > > > I'm a little concerned about the backwards-compatibility implications of > > this change. Though I agree the new behaviour is entirely sane perhaps > > it should be activated via a new command line option. > > I did not notice this problem until Jan reported it so I thouhgt that it > is just a hidden assumption, people might not notice it and use it that > way. > > For Fedora/RHEL kdump we will copy 1st kernel cmdline by default so one > do not need to use it. For kexec and other distributions I'm not sure.. > > Since it is more of a fix to original logic, personally I tend to not > introducing a new option. But if you think we need to add a new option I > can do it. > > Also, won't this affect other architectures that use DT. > > I'm thinking about ARM. If so it might be good to tweak the changelog. > > arm also uses the function, but I need verify the behavior. Will tune the > changelog after I confirming it. Thanks I'm still concerned that people may be relying on this behaviour. But I agree it seems painful to add an option to get what should have been the default.
