On 19.02.25 13:49, Dave Young wrote:
On Wed, 19 Feb 2025 at 15:32, Mike Rapoport <rppt@xxxxxxxxxx> wrote:
On Mon, Feb 17, 2025 at 11:19:45AM +0800, RuiRui Yang wrote:
On Thu, 6 Feb 2025 at 21:34, Mike Rapoport <rppt@xxxxxxxxxx> wrote:
== Limitations ==
Currently KHO is only implemented for file based kexec. The kernel
interfaces in the patch set are already in place to support user space
kexec as well, but it is still not implemented it yet inside kexec tools.
What architecture exactly does this KHO work fine? Device Tree
should be ok on arm*, x86 and power*, but how about s390?
KHO does not use device tree as the boot protocol, it uses FDT as a data
structure and adds architecture specific bits to the boot structures to
point to that data, very similar to how IMA_KEXEC works.
Currently KHO is implemented on arm64 and x86, but there is no fundamental
reason why it wouldn't work on any architecture that supports kexec.
Well, the problem is whether there is a way to add dtb in the early
boot path, for X86 it is added via setup_data, if there is no such
way I'm not sure if it is doable especially for passing some info for
early boot use. Then the KHO will be only for limited use cases.
Every architecture has a platform specific way of passing data into the
kernel so it can find its command line and initrd. S390x for example has
struct parmarea. To enable s390x, you would remove some of its padding
and replace it with a KHO base addr + size, so that the new kernel can
find the KHO state tree.
Alex
