MIPS: Make the debugging of compressed kernel configurable

This patch adds a new DEBUG_ZBOOT option to allow the users to enable it
to debug the compressed kernel support for a new board and this optoin
should be disabled to reduce the kernel image size and speed up the
kernel booting procedure when the compressed kernel support is stable.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Manuel Lauss <manuel.lauss@googlemail.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/918/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig.debug

@@ -102,4 +102,23 @@ config RUNTIME_DEBUG
 	  arch/mips/include/asm/debug.h for debugging macros.
 	  If unsure, say N.
 
+config DEBUG_ZBOOT
+	bool "Enable compressed kernel support debugging"
+	depends on DEBUG_KERNEL && SYS_SUPPORTS_ZBOOT
+	default n
+	help
+	  If you want to add compressed kernel support to a new board, and the
+	  board supports uart16550 compatible serial port, please select
+	  SYS_SUPPORTS_ZBOOT_UART16550 for your board and enable this option to
+	  debug it.
+
+	  If your board doesn't support uart16550 compatible serial port, you
+	  can try to select SYS_SUPPORTS_ZBOOT and use the other methods to
+	  debug it. for example, add a new serial port support just as
+	  arch/mips/boot/compressed/uart-16550.c does.
+
+	  After the compressed kernel support works, please disable this option
+	  to reduce the kernel image size and speed up the booting procedure a
+	  little.
+
 endmenu

arch/mips/boot/compressed/Makefile

@@ -35,8 +35,10 @@ KBUILD_AFLAGS := $(LINUXINCLUDE) $(KBUILD_AFLAGS) -D__ASSEMBLY__ \
 
 obj-y := $(obj)/head.o $(obj)/decompress.o $(obj)/dbg.o
 
+ifdef CONFIG_DEBUG_ZBOOT
 obj-$(CONFIG_SYS_SUPPORTS_ZBOOT_UART16550) += $(obj)/uart-16550.o
 obj-$(CONFIG_MACH_ALCHEMY)		   += $(obj)/uart-alchemy.o
+endif
 
 OBJCOPYFLAGS_vmlinux.bin := $(OBJCOPYFLAGS) -O binary -R .comment -S
 $(obj)/vmlinux.bin: $(KBUILD_IMAGE)