Submitted as http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2006-June/034667.html

Include a fixup machine start function in nslu2-setup.c to handle
the command line and memory setup parameters which are not specifiable
in the boot loader.

Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Rod Whitby <rod@whitby.id.au>

 arch/arm/mach-ixp4xx/nslu2-setup.c |   45 ++++++++++++++++++++++++++++++++++++-
 1 files changed, 44 insertions(+), 1 deletion(-)

Index: linux-2.6.17/arch/arm/mach-ixp4xx/nslu2-setup.c
===================================================================
--- linux-2.6.17.orig/arch/arm/mach-ixp4xx/nslu2-setup.c
+++ linux-2.6.17/arch/arm/mach-ixp4xx/nslu2-setup.c
@@ -19,6 +19,8 @@
 #include <linux/serial_8250.h>
 #include <linux/leds.h>
 
+#include <asm/setup.h>
+#include <asm/memory.h>
 #include <asm/mach-types.h>
 #include <asm/mach/arch.h>
 #include <asm/mach/flash.h>
@@ -243,11 +245,52 @@
 	platform_add_devices(nslu2_devices, ARRAY_SIZE(nslu2_devices));
 }
 
+/*
+ * NSLU2 RedBoot passes garbage atag/parameter values because it copies
+ * the kernel zImage on top of the parameter list before branching into
+ * the zImage.  The machine description causes the ATAG list to be
+ * skipped (by setting boot_params to 0) and this code fixes up the
+ * memory info and command line by supplying a command line with the
+ * NSLU2 specific config prepended.
+ *
+ * NOTE: the startup sequence is:
+ * 	1) Call the machine fixup
+ * 	2) Parse the ATAG list, the ATAG_CMDLINE is copied in
+ * 	   to default_command_line which is the value of *from
+ * 	3) Parse the command line in *from (*not*
+ * 	   default_command_line unless they are the same!)
+ *
+ * Setting mi->nr_banks causes (2) to 'squash' (set to ATAG_NONE)
+ * any ATAG_MEM tags, but mem= command line options cause nr_banks
+ * to be reset to 0 (on the first mem=)
+ */
+static char nslu2_command_line[] __initdata =
+	"root=/dev/mtdblock4 rootfstype=jffs2 init=/linuxrc "
+	"rtc-x1205.probe=0,0x6f "
+	CONFIG_CMDLINE;
+
+static void __init nslu2_fixup(struct machine_desc *desc,
+		struct tag *tags, char **cmdline, struct meminfo *mi)
+{
+	/* The NSLU2 has one bank of 32MByte memory.
+	 * NOTE: to make a 'fatslug' work append the appropriate
+	 * mem= to the CONFIG_CMDLINE - this will override the
+	 * setting below.
+	 */
+	mi->nr_banks=1;
+	mi->bank[0].start = 0;
+	mi->bank[0].size = (32*1024*1024);
+	mi->bank[0].node = PHYS_TO_NID(0);
+
+	strlcpy(*cmdline, nslu2_command_line, COMMAND_LINE_SIZE);
+}
+
 MACHINE_START(NSLU2, "Linksys NSLU2")
 	/* Maintainer: www.nslu2-linux.org */
 	.phys_io	= IXP4XX_PERIPHERAL_BASE_PHYS,
 	.io_pg_offst	= ((IXP4XX_PERIPHERAL_BASE_VIRT) >> 18) & 0xFFFC,
-	.boot_params	= 0x00000100,
+	.boot_params    = 0, /* because they are garbage - see above */
+	.fixup          = nslu2_fixup,
 	.map_io		= ixp4xx_map_io,
 	.init_irq	= ixp4xx_init_irq,
 	.timer          = &ixp4xx_timer,