qemu/powerpc64-pseries: add new sample config

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

board/qemu/powerpc64-pseries/readme.txt

@@ -0,0 +1,7 @@
+Run the emulation with:
+
+ qemu-system-ppc64 -M pseries -cpu POWER7 -m 256 -kernel output/images/vmlinux -append 'console=hvc0 root=/dev/sda' -drive file=output/images/rootfs.ext2,if=scsi,index=0 -serial stdio -display curses
+
+The login prompt will appear in the terminal that started Qemu.
+
+Tested with QEMU 2.1.0

configs/qemu_ppc64_pseries_defconfig

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+# Architecture
+BR2_powerpc64=y
+BR2_powerpc_power7=y
+
+# System
+BR2_TARGET_GENERIC_GETTY=y
+BR2_TARGET_GENERIC_GETTY_PORT="hvc0"
+
+# Filesystem
+BR2_TARGET_ROOTFS_EXT2=y
+# BR2_TARGET_ROOTFS_TAR is not set
+
+# Lock to 3.16 headers to avoid breaking with newer kernels
+BR2_KERNEL_HEADERS_VERSION=y
+BR2_DEFAULT_KERNEL_VERSION="3.16.1"
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_16=y
+
+# Kernel
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="3.16.1"
+BR2_LINUX_KERNEL_DEFCONFIG="pseries"
+BR2_LINUX_KERNEL_VMLINUX=y