On Fri, 2023-10-20 at 18:12 +0300, Kirill A. Shutemov wrote: > ACPI MADT doesn't allow to offline CPU after it got woke up. It limits > kexec: the second kernel won't be able to use more than one CPU. > > Now acpi_mp_wake_mailbox_paddr already has the mailbox address. > The acpi_wakeup_cpu() will use it to bring up secondary cpus. > > Zero out mailbox address in the ACPI MADT wakeup structure to indicate > that the mailbox is not usable. This prevents the kexec()-ed kernel > from reading a vaild mailbox, which in turn makes the kexec()-ed kernel > only be able to use the boot CPU. > > This is Linux-specific protocol and not reflected in ACPI spec. > > Booting the second kernel with signle CPU is enough to cover the most > common case for kexec -- kdump. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx> _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
