[U-Boot] [PATCH 2/2] ARM: qemu-arm: define fdt_addr_r

[AKASHI Takahiro]

On Mon, Oct 15, 2018 at 04:01:06AM +0300, Tuomas Tynkkynen wrote:
> Hi Takahiro,
> 
> On Fri, 12 Oct 2018 14:07:57 +0900
> AKASHI Takahiro <takahiro.akashi at linaro.org> wrote:
> 
> > This variable, fdt_addr_t, is missing in the current qemu-arm.h while
> > it seems to be mandatory, at least, to run distro_bootcmd as expected.
> > So just add its definition. A size of 1MB would be enough.
> > 
> 
> In what way is this required for distro_bootcmd to work? At least in the
> past I've tested qemu_arm64_defconfig and EFI boot with the Fedora
> netinst image and it has worked fine in stock U-Boot.
> 
> Note that these '-machine virt' based targets are slightly different
> from real hardware in the sense that instead of loading a .dtb file
> provided by the OS, the device tree is provided by QEMU. In the hunk
> below you can see "fdt_addr=0x40000000\0" providing the address of
> the QEMU-provided device tree which the distro scripts should be
> using.

Yep, I know that.
I was not clear; what distro bootcmd, or more specifically scan_dev_for_efi,
tries to do regarding fdt handling is that, if "fdtfile" variable is defined,
it supersedes qemu's own dtb (that is what "fdt_addr" points to), but
this trick doesn't work expectedly if "fdt_addr_r" variable is not defined.

> I guess in principle having ${fdt_addr_r} set as well shouldn't hurt and
> might be used for testing/unusual purposes.

I don't know whether the case is "unsual" or not.
But doc/README.distro cleary says that fdt_addr_r is *mandatory*.
If u-boot works without it, it's a bug, otherwise we must correct
the doc (or scan_dev_for_efi in the first place?).

Thanks,
-Takahiro Akashi

> Glancing at cmd/pxe.c,
> there is a problem though, in that if ${fdt_addr_r} were defined, a PXE
> file using the FDTDIR directive would attempt loading a dtb file named
> "<NULL>-qemu-arm.dtb" instead of falling back to using ${fdt_addr}.
> That bug would need to be fixed first before applying this patch.
>
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> > ---
> >  include/configs/qemu-arm.h | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/include/configs/qemu-arm.h b/include/configs/qemu-arm.h
> > index 91fb8d47edf8..0e66f946dde5 100644
> > --- a/include/configs/qemu-arm.h
> > +++ b/include/configs/qemu-arm.h
> > @@ -55,6 +55,7 @@
> >  	"fdt_high=0xffffffff\0" \
> >  	"initrd_high=0xffffffff\0" \
> >  	"fdt_addr=0x40000000\0" \
> > +	"fdt_addr_r=0x40100000\0" \
> >  	"scriptaddr=0x40200000\0" \
> >  	"pxefile_addr_r=0x40300000\0" \
> >  	"kernel_addr_r=0x40400000\0" \
>