[PATCH RESEND] x86/kexec: Carry forward the boot DTB on kexec

[Baoquan He]

On 08/01/25 at 07:24pm, Brian Mak wrote:
> On Jul 31, 2025, at 8:02 PM, Baoquan He <bhe at redhat.com> wrote:
> 
> > On 07/29/25 at 11:21am, Brian Mak wrote:
> >> The kexec_file_load syscall on x86 currently does not support passing
> >> a device tree blob to the new kernel.
> >> 
> >> To add support for this, we copy the behavior of ARM64 and PowerPC and
> >> copy the current boot's device tree blob for use in the new kernel. We
> >> do this on x86 by passing the device tree blob as a setup_data entry in
> >> accordance with the x86 boot protocol.
> > 
> > I see how, but no why. Why do we need to add DTB for x86?
> 
> Hi Baoquan,
> 
> Thanks for your comment. Some embedded x86 systems, such as ours at
> Juniper, use device trees. Currently, the x86 kexec_file_load syscall
> has no support for passing the device tree to the new kernel, which is a
> problem for us since we use kexec for some software upgrade related
> features. Not passing a device tree to the new kernel would cause a boot
> failure here.

Thanks for the info. Please add these into patch log to let reviewers
know them. We don't add code w/o objective.