On Wed, Sep 05, 2018 at 11:04:36AM -0700, Scott Branden wrote: > On 18-09-05 11:00 AM, Grant Likely wrote: > > On Wed, Sep 5, 2018 at 6:27 PM Scott Branden <scott.bran...@broadcom.com> > > wrote: > > > On 18-09-05 02:40 AM, Ard Biesheuvel wrote: > > > > On 4 September 2018 at 19:19, Scott Branden > > > > <scott.bran...@broadcom.com> wrote: > > > > > Rather than introduce EFI_ARMSTUB_DTB_LOADER, why not have > > > > > the efistub use CONFIG_OF to determine whether it supports dtb= or > > > > > not? > > > > > > > > > > That way ACPI-only distros disable devicetree support entirely. > > > > > > > > > Unfortunately, CONFIG_OF cannot be disabled on arm64 even on ACPI-only > > > > builds. > > > OF shouldn't be automatically selected in the arm64/Kconfig. It should > > > have a config parmaeter like other archs as mips and arm. I can > > > submit a patch so it functions the same way as other archs so it > > > is not always selected. It will be good to add a USE_OF config > > > options like the other archs (or simply remove the select from the > > > Kconfig and choose OF directly in the defconfig. This will have > > > the added benefit of doing away with OF support when its not > > > needed on an ARM64 platform. ACPI is already not automatically > > > selected for all ARM64 platforms, nor should devicetree. > > We don't do that on Arm because a devicetree is always required at > > boot time. Even on ACPI systems a tiny DTB is used containing just a > > /chosen node for passing the kernel command line and the initrd > > location. > > Seems bizarre DTB is not needed for x86 to boot from UEFI with ACPI > support? I'll look into it further at some point in order to remove such > anomaly. There should be no need for such devicetree reliance.
I'd say don't waste time on this, the patch would not get merged ;). As Grant said, we use a tiny dtb to pass the command line, initrd to the kernel. You'd have to invent an alternative (setup_header, ATAGs) and I really don't see the point of increased complexity just because of some philosophical arguments against OF. -- Catalin
