[PATCH] kexec: Add option to fallback to old kexec syscall when kexec file based syscall failed

[Petr Tesarik]

On Fri, 15 Jul 2016 18:28:05 +0800
joeyli <jlee at suse.com> wrote:

> On Fri, Jul 15, 2016 at 09:58:22AM +0200, Petr Tesarik wrote:
> > On Fri, 15 Jul 2016 07:57:22 +0800
> > joeyli <jlee at suse.com> wrote:
> > 
> > > Hi Vivek
> > > 
> > > On Thu, Jul 14, 2016 at 10:53:28AM -0400, Vivek Goyal wrote:
> > > > On Thu, Jul 14, 2016 at 04:45:11PM +0800, Lee, Chun-Yi wrote:
> > > > > This patch adds a new "--fallback-kexec" option to give a chance to
> > > > > fallback to old kexec syscall when file based kexec syscall operation
> > > > > failed.
> > > > 
> > > > I think caller should switch to using different interface if need be. But
> > > > I don't see much point in providing an option for this in kexec-tools.
> > > > 
> > > > Vivek
> > > >
> > > 
> > > OK~ Understood!
> > > 
> > > Thanks for Baoquan's and your opinion for this patch.
> > 
> > Is there some sort of diagnostics, so a calling script can determine
> > whether kexec failed, because there's no suppor for kexec_file_load(2)
> > or for a different reason? 
> > 
> > Thanks,
> > Petr T
> 
> The calling script needs to use "-s" option to access file based kexec, then
> check the result

This is the part I was asking about. How do I "check the result"? In
other words, what is "the result" if kexec fails because of missing
kernel syscall, and what is "the result" if it fails for any other
reason (e.g. insufficient privileges)?

Or do you suggest that the script always retrius without "-s" after
"kexec -s" fails, just in case loading might work the old way?

Petr T

> and call kexec without -s to access old kexec syscall.
> 
> With this patch is just more convenience.
> 
> 
> Thanks a lot!
> Joey Lee