The first patch defines a specialized machine emergency restart callback not to write to the physical address of 0x472 which is what the native_machine_emergency_restart() does unconditionally. I first wanted to tweak that function[1], and in the course of the discussion it looked as the risks of doing that would outweigh the benefit: the bare-metal systems have likely adopted that behavior as a standard although I could not find any mentions of that magic address in the UEFI+ACPI specification. The second patch removes the need to always supply "reboot=t" to the kernel command line in the OpenHCL bootloader[2]. There is no other option at the moment; when/if it appears the newly added callback's code can be adjusted as required. Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx> [1] https://lore.kernel.org/all/20250109204352.1720337-1-romank@xxxxxxxxxxxxxxxxxxx/ [2] https://github.com/microsoft/openvmm/blob/7a9d0e0a00461be6e5f3267af9ea54cc7157c900/openhcl/openhcl_boot/src/main.rs#L139 [V2]: - Fixed the warning from the kernel robot about using C23. ** Thank you, kernel robot!** - Tightened up wording in the comments and the commit descriptions. ** Thank you, Saurabh!** - Dropped the CC: stable tag as there is no specific commit this patch series fixes. ** Thank you, Saurabh!** [V1]: https://lore.kernel.org/linux-hyperv/20250117210702.1529580-1-romank@xxxxxxxxxxxxxxxxxxx/ Roman Kisel (2): x86/hyperv: VTL mode emergency restart callback x86/hyperv: VTL mode callback for restarting the system arch/x86/hyperv/hv_vtl.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) base-commit: 3a7f7785eae7cf012af128ca9e383c91e4955354 -- 2.43.0
