Re: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down

From	Dave Young <dyoung@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down
Date	2017-04-07 08:40 +0200
Message-ID	<ttvIS-3yA-11@gated-at.bofh.it> (permalink)
References	<tsZzj-7hF-5@gated-at.bofh.it> <tsZzk-7hF-23@gated-at.bofh.it> <ttlzQ-5bW-7@gated-at.bofh.it>
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On 04/06/17 at 09:43pm, Rafael J. Wysocki wrote:
> On Wed, Apr 5, 2017 at 10:16 PM, David Howells <dhowells@redhat.com> wrote:
> > From: Josh Boyer <jwboyer@redhat.com>
> >
> > 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.

> 
> Thanks,
> Rafael
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Thread

[PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel  has been locked down David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  Re: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel  has been locked down "Rafael J. Wysocki" <rafael@kernel.org> - 2017-04-06 21:50 +0200
    Re: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the  kernel has been locked down Dave Young <dyoung@redhat.com> - 2017-04-07 08:40 +0200
      Re: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down David Howells <dhowells@redhat.com> - 2017-04-07 09:10 +0200
        Re: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the  kernel has been locked down Dave Young <dyoung@redhat.com> - 2017-04-07 09:50 +0200

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