Re: [PATCH FOR-4.5] xen: arm: Do not enable EFI in dom0 since it is not yet supported.

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2014-10-14 at 13:58 +0100, Julien Grall wrote:
> On 10/14/2014 01:49 PM, Ian Campbell wrote:
> > On Tue, 2014-10-14 at 13:28 +0100, Julien Grall wrote:
> >> Hi Ian,
> >>
> >> On 10/14/2014 08:21 AM, Ian Campbell wrote:
> >>> On Mon, 2014-10-13 at 12:37 -0700, Roy Franz wrote:
> >>>> On Mon, Oct 13, 2014 at 9:20 AM, Julien Grall <julien.grall@linaro.org> wrote:
> >>>>> (CC vijay)
> >>>>>
> >>>>> Hi Suravee,
> >>>>>
> >>>>> On 10/13/2014 05:17 PM, suravee.suthikulpanit@amd.com wrote:
> >>>>>> From: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> >>>>>>
> >>>>>> Since EFI is not yet supported in dom0, we need to remove the following
> >>>>>> properties from the chosen node:
> >>>>>>
> >>>>>>   * linux,uefi-mmap-start
> >>>>>>   * linux,uefi-mmap-size
> >>>>>>   * linux,uefi-mmap-desc-size
> >>>>>>   * linux,uefi-mmap-desc-ver
> >>>>>>
> >>>>>> These are added by "arch/arm/efi/efi-boot.h: fdt_add_uefi_nodes()",
> >>>>>> and used by dom0 kernel to enable EFI.
> >>>>>>
> >>>>>> Cc: Julien Grall <julien.grall@linaro.org>
> >>>>>> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> >>>>>> Cc: Ian Campbell <ian.campbell@citrix.com>
> >>>>>> Cc: Roy Franz <roy.franz@linaro.org>
> >>>>>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> >>>>>
> >>>>> Reviewed-by: Julien Grall <julien.grall@linaro.org>
> >>>>
> >>>> Reviewed-by: Roy Franz <roy.franz@linaro.org>
> >>>
> >>> Acked-by: Ian Campbell <ian.campbell@.citrix.com>
> >>>
> >>> But I do wonder why we don't just drop the hos /chosen node -- I think
> >>> everything which should be in there is fabricated by the h/visor anyway.
> >>
> >> I though about the same things yesterday, but the /chosen node may
> >> contain other properties (such as OS specific) that we may need to pass
> >> to DOM0.
> > 
> > What sort of thing are you thinking of here?
> 
> FreeBSD provides two properties (stdin and stdout) to choose the input
> and the output methods.
> 
> Those properties need to be copied in DOM0 DT to allow the user chose
> which console he wants to use (think about a platform with 2 serial ports).

How do you know whether stdin/stdout were intended to apply to dom0 or
Xen?

What if dom0 wants to use hvc0? How is that expressed?

It seems to me that if bootargs is being consumed by Xen then
stdin/stdout ought to be consumed by Xen for consistency.

Which points to special handling for stdin/stdout in Xen, i.e. a
continuation of the whitelisting approach.

Ian.