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

[AKASHI Takahiro]

On Thu, Oct 18, 2018 at 09:25:04AM +0200, Alexander Graf wrote:
> 
> 
> On 18.10.18 00:25, Tuomas Tynkkynen wrote:
> > Hi Alexander,
> > 
> > On Tue, 16 Oct 2018 15:04:26 +0200
> > Alexander Graf <agraf at suse.de> wrote:
> > 
> > ...
> >>>   
> >>>> 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.  
> >>
> >> Well, and that load will fail and everyone's happy, no? 
> > 
> > No, because currently if DTB loading from the filesystem/tftp is
> > attempted and it fails, it aborts the boot. It doesn't matter if it's
> > via a 'FDT' or 'FDTDIR' directive. In the case of typical hardware
> > that's probably the desired behaviour.
> > 
> > I guess the qemu_arm + FDTDIR case can be fixed by not attempting
> > a .dtb load if the default fdtfile is not known due to $soc or $board
> > being unset. At least I doubt that some other board could be relying
> > on a filename containing literally "<NULL>" :)
> 
> Well - IIRC $soc and $board should also always be defined ;). So yet
> another thing to fix in the QEMU port.

See my patch below. Are you happy with it?
(qemu-qemu-arm.dtb doesn't make sense to me, though :)

> > 
> >> IMHO we should
> >> fall back to $fdtcontroladdr always
> > 
> > FWIW, to me the idea of passing $fdtcontroladdr to the OS has always
> > filled me with dread. On top of the usual backwards- and
> > forwards-compatibility problems that happen when mixing and matching
> > kernels and DTBs from different releases, you now have to deal with
> 
> That's something that we seriously as a community need to get sorted
> out. We're pushing hard for it in the EBBR context. The fact that people
> are afraid of putting *hardware desciption* into their firmware is just
> mind boggling.

I don't have a strong opinion, but it seems to me that 'fall-back' approach
is quite normal. If it doesn't work on a specific board, 'fdt_addr'
should be defined.

Thanks,
-Takahiro Akashi


> > issues like U-Boot specific .dts that are majorly diverged from Linux
> > ones, or where the .dts is otherwise from Linux but the U-Boot specific
> 
> These case should really be the minority. And if you see those, please
> fix them.
> 
> > additions break it for Linux, or where the .dts used is wrong for the
> 
> I've never seen a case where a U-Boot addition broke the DT for Linux.
> 
> > specific hardware revision but close enough for U-Boot's purposes,
> > and so on...
> 
> Again, something that just needs fixing. Device trees belong to the
> entity that knows hardware, not to the OS. Otherwise you lose the
> abstraction layer that DT gives you and you lose the ability to run
> "generic" kernels. And of course you break the ecosystem, because now
> good luck running BSD, your own little toy OS, etc ;)
> 
> 
> Alex

===8<===
>From 47b26a86359a3b612e890f2ca2d5d20092f9f4e1 Mon Sep 17 00:00:00 2001
From: AKASHI Takahiro <takahiro.akashi at linaro.org>
Date: Fri, 19 Oct 2018 15:22:02 +0900
Subject: [PATCH] arm: qemu: rework Kconfig

Define SYS_SOC and move SYS_* to a canonical place (under board).

Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
 arch/arm/mach-qemu/Kconfig       | 18 ++++++++++--------
 board/emulation/Kconfig          |  2 ++
 board/emulation/qemu-arm/Kconfig |  9 +++++++++
 3 files changed, 21 insertions(+), 8 deletions(-)
 create mode 100644 board/emulation/qemu-arm/Kconfig

diff --git a/arch/arm/mach-qemu/Kconfig b/arch/arm/mach-qemu/Kconfig
index a2e4b98b8887..d75a95183a75 100644
--- a/arch/arm/mach-qemu/Kconfig
+++ b/arch/arm/mach-qemu/Kconfig
@@ -3,22 +3,24 @@ if ARCH_QEMU
 config SYS_VENDOR
 	default "emulation"
 
-config SYS_BOARD
-	default "qemu-arm"
+config SYS_SOC
+	default "qemu"
 
-config SYS_CONFIG_NAME
-	default "qemu-arm"
-
-endif
+choice
+	prompt "QEMU cpu type"
 
 config TARGET_QEMU_ARM_32BIT
-	bool "Support qemu_arm"
+	bool "Arm"
 	depends on ARCH_QEMU
 	select ARCH_SUPPORT_PSCI
 	select CPU_V7A
 	select SYS_ARCH_TIMER
 
 config TARGET_QEMU_ARM_64BIT
-	bool "Support qemu_arm64"
+	bool "AArch64"
 	depends on ARCH_QEMU
 	select ARM64
+
+endchoice
+
+endif
diff --git a/board/emulation/Kconfig b/board/emulation/Kconfig
index f821458fa6ac..597e926cdb11 100644
--- a/board/emulation/Kconfig
+++ b/board/emulation/Kconfig
@@ -27,4 +27,6 @@ endchoice
 
 source "board/emulation/qemu-x86/Kconfig"
 
+source "board/emulation/qemu-arm/Kconfig"
+
 endif
diff --git a/board/emulation/qemu-arm/Kconfig b/board/emulation/qemu-arm/Kconfig
new file mode 100644
index 000000000000..db8b2a4dfae2
--- /dev/null
+++ b/board/emulation/qemu-arm/Kconfig
@@ -0,0 +1,9 @@
+if TARGET_QEMU_ARM_32BIT || TARGET_QEMU_ARM_64BIT
+
+config SYS_BOARD
+	default "qemu-arm"
+
+config SYS_CONFIG_NAME
+	default "qemu-arm"
+
+endif
-- 
2.19.0