Messages in this thread | | | From | Ard Biesheuvel <> | Date | Sun, 9 Sep 2018 17:55:55 +0200 | Subject | Re: [PATCH] arm64: defconfig: enable EFI_ARMSTUB_DTB_LOADER |
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On 9 September 2018 at 13:07, Catalin Marinas <catalin.marinas@arm.com> wrote: > 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.branden@broadcom.com> wrote: >> > > On 18-09-05 02:40 AM, Ard Biesheuvel wrote: >> > > > On 4 September 2018 at 19:19, Scott Branden <scott.branden@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. >
Not just that: we also need of_match_table support for ACPI's PRP0001 device (which is a horrible hack in itself, but currently supported in Linux/arm64 *and* Linux/x86 nonetheless)
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