Re: [PATCH 2/3] powerpc/e500: add paravirt QEMU platform

From: Alexander Graf <hidden>
Date: 2012-07-06 12:29:24

On 28.06.2012, at 01:50, Scott Wood wrote:

This gives the kernel a paravirtualized machine to target, without
requiring both sides to pretend to be targeting a specific board
that likely has little to do with the host in KVM scenarios.  This
avoids the need to add new boards to QEMU just to be able to
run KVM on new CPUs.
=20
As this is the first platform that can run with either e500v2 or
e500mc, CONFIG_PPC_E500MC is now a legitimately user configurable
option, so add a help text.
=20
Signed-off-by: Scott Wood <redacted>
---
arch/powerpc/platforms/85xx/Kconfig     |   16 +++++++
arch/powerpc/platforms/85xx/Makefile    |    1 +
arch/powerpc/platforms/85xx/qemu_e500.c |   66 =

+++++++++++++++++++++++++++++++

arch/powerpc/platforms/Kconfig.cputype  |    4 ++

I really think we should document what exactly this machine expects.

quoted hunk ↗ jump to hunk

4 files changed, 87 insertions(+), 0 deletions(-)
create mode 100644 arch/powerpc/platforms/85xx/qemu_e500.c
=20

diff --git a/arch/powerpc/platforms/85xx/Kconfig =

b/arch/powerpc/platforms/85xx/Kconfig

quoted hunk ↗ jump to hunk

index f000d81..7bbebe5 100644

--- a/arch/powerpc/platforms/85xx/Kconfig
+++ b/arch/powerpc/platforms/85xx/Kconfig

@@ -263,6 +263,22 @@ config P5020_DS

	help
	  This option enables support for the P5020 DS board
=20
+config PPC_QEMU_E500
+	bool "QEMU generic e500 platform"
+	depends on EXPERIMENTAL
+	select DEFAULT_UIMAGE
+	help
+	  This option enables support for running as a QEMU guest using
+	  QEMU's generic e500 machine.  This is not required if you're
+	  using a QEMU machine that targets a specific board, such as
+	  mpc8544ds.
+
+	  Unlike most e500 boards that target a specific CPU, this
+	  platform works with any e500-family CPU that QEMU supports.
+	  Thus, you'll need to make sure CONFIG_PPC_E500MC is set or
+	  unset based on the emulated CPU (or actual host CPU in the =

case

quoted hunk ↗ jump to hunk

+	  of KVM).
+
endif # FSL_SOC_BOOKE
=20
config TQM85xx

diff --git a/arch/powerpc/platforms/85xx/Makefile =

b/arch/powerpc/platforms/85xx/Makefile

quoted hunk ↗ jump to hunk

index 2125d4c..f841ac8 100644

--- a/arch/powerpc/platforms/85xx/Makefile
+++ b/arch/powerpc/platforms/85xx/Makefile

@@ -28,3 +28,4 @@ obj-$(CONFIG_SOCRATES)    +=3D socrates.o =

socrates_fpga_pic.o

quoted hunk ↗ jump to hunk

obj-$(CONFIG_KSI8560)	  +=3D ksi8560.o
obj-$(CONFIG_XES_MPC85xx) +=3D xes_mpc85xx.o
obj-$(CONFIG_GE_IMP3A)	  +=3D ge_imp3a.o
+obj-$(CONFIG_PPC_QEMU_E500) +=3D qemu_e500.o

diff --git a/arch/powerpc/platforms/85xx/qemu_e500.c =

b/arch/powerpc/platforms/85xx/qemu_e500.c

quoted hunk ↗ jump to hunk

new file mode 100644
index 0000000..77c8d5d

--- /dev/null
+++ b/arch/powerpc/platforms/85xx/qemu_e500.c

@@ -0,0 +1,66 @@
+/*
+ * Paravirt target for a generic QEMU e500 machine
+ *
+ * Copyright 2012 Freescale Semiconductor Inc.
+ *
+ * This program is free software; you can redistribute  it and/or =

modify it

+ * under  the terms of  the GNU General  Public License as published =

by the

+ * Free Software Foundation;  either version 2 of the  License, or =

(at your

+ * option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/of_fdt.h>
+#include <asm/machdep.h>
+#include <asm/time.h>
+#include <asm/udbg.h>
+#include <asm/mpic.h>
+#include <sysdev/fsl_soc.h>
+#include <sysdev/fsl_pci.h>
+#include "smp.h"
+#include "mpc85xx.h"
+
+void __init qemu_e500_pic_init(void)
+{
+	struct mpic *mpic;
+
+	mpic =3D mpic_alloc(NULL, 0, MPIC_BIG_ENDIAN | =

MPIC_SINGLE_DEST_CPU,

+			0, 256, " OpenPIC  ");

Does that mean we're configuring the MPIC regardless of what the guest =
tells us? So the MPIC is a hard requirement. We can't use UIC or XPIC =
with this machine, right? This needs to be documented.

+
+	BUG_ON(mpic =3D=3D NULL);
+	mpic_init(mpic);
+}
+
+static void __init qemu_e500_setup_arch(void)
+{
+	ppc_md.progress("qemu_e500_setup_arch()", 0);
+
+	fsl_pci_init();
+	mpc85xx_smp_init();
+}
+
+/*
+ * Called very early, device-tree isn't unflattened
+ */
+static int __init qemu_e500_probe(void)
+{
+	unsigned long root =3D of_get_flat_dt_root();
+
+	return !!of_flat_dt_is_compatible(root, "fsl,qemu-e500");

So the machine needs to be compatible "fsl,qemu-e500". Needs =
documentation in the machine spec.

I'm sure you'll find more constraints that appear logical, but really =
should be written down so we have something formal that potentially =
someone not-QEMU or not-Scott could write a machine implementation =
against ;).


Alex

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