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    SubjectRe: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down
    On 04/07/17 at 08:05am, David Howells wrote:
    > Dave Young <dyoung@redhat.com> wrote:
    >
    > > > > This option allows userspace to pass the RSDP address to the kernel, which
    > > > > makes it possible for a user to circumvent any restrictions imposed on
    > > > > loading modules. Ignore the option when the kernel is locked down.
    > > >
    > > > I'm not really sure here.
    > > >
    > > > What exactly is the mechanism?
    > >
    > > Actually this acpi_rsdp param is created for EFI kexec reboot in old
    > > days when we had not supported persistent efi vm space across kexec
    > > reboot. At that time kexec reboot runs as noefi mode, it can not find
    > > the acpi root table thus kernel will hang early.
    > >
    > > Now kexec can support EFI boot so this param is not necessary for most
    > > user unless they still use efi=old_map.
    >
    > Is this patch now unnecessary?

    I think it is still necessary because the acpi_rsdp kernel param is still
    a valid paramater and one can still pass a pointer to be recognized as acpi
    root pointer.

    Maybe "imposed on loading modules" is not clear which can be dropped.

    Thanks
    Dave

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