On Mon, Feb 12 2024 at 12:44, Kirill A. Shutemov wrote: > ACPI MADT doesn't allow to offline a CPU after it was onlined. This > limits kexec: the second kernel won't be able to use more than one CPU. > > To prevent a kexec kernel from onlining secondary CPUs invalidate the > mailbox address in the ACPI MADT wakeup structure which prevents a > kexec kernel to use it. > > This is safe as the booting kernel has the mailbox address cached > already and acpi_wakeup_cpu() uses the cached value to bring up the > secondary CPUs. > > Note: This is a Linux specific convention and not covered by the > ACPI specification. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx> > Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
