HACK: Pass data from firmware to kernel

arch/arm/lib/bootm.c

Index: arch/arm/lib/bootm.c
diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index e7d047a274b348850a6bfebddef164fe1af9439e..59204f9ee7cea2fc73feefc476ba66287dd6d49f 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -30,6 +30,17 @@
 #include <libfdt.h>
 #include <fdt_support.h>
 
+/*
+ * TODO(clchiou): This is an urgent hack for bringing up factory. We need to
+ * enable setup memory tags.
+ *
+ * Remove this part or move to config headers after the protocol specification
+ * between Chrome OS firmware and kernel is finalized.
+ */
+#ifndef CONFIG_SETUP_MEMORY_TAGS
+#define CONFIG_SETUP_MEMORY_TAGS

[Vincent Palatin, 2011/04/07 13:26:56]

As we are also using "mem=" command line parameter, this will declare all memory
banks twice in the meminfo kernel structure.
Does this really work ?

[Che-Liang Chiou, 2011/04/08 07:41:15]

Good point. Thanks a lot. I will use "mem=" then.

By the way, I have another question:
We setup "mem=" twice in bootargs "mem=384M@0M nvmem=128M@384M mem=512M@512M"
when booting kernel. Does that mean the kernel will try the first and then the
second?

+#endif
+
 DECLARE_GLOBAL_DATA_PTR;
 
 #if defined (CONFIG_SETUP_MEMORY_TAGS) || \
@@ -267,6 +278,17 @@ static void setup_memory_tags (bd_t *bd)
 		params->u.mem.start = bd->bi_dram[i].start;
 		params->u.mem.size = bd->bi_dram[i].size;
 
+		/*
+		 * TODO(clchiou): This is an urgent hack for bringing up
+		 * factory. Here we reserve 1MB static area for passing data
+		 * from firmware to kernel.
+		 *
+		 * Rewrite this part after the protocol specification between
+		 * Chrome OS firmware and kernel is finalized.
+		 */
+		if (i == CONFIG_NR_DRAM_BANKS - 1)

[Vincent Palatin, 2011/04/07 13:26:56]

IMHO it would be as easy and less hackish to add a custom tag with your custom
firmware information in the atag chained list.

[Che-Liang Chiou, 2011/04/08 07:41:15]

I was not sure whether kernel treat unrecognized ATAGs (drop it or ignore it?).
Do you have an idea about that?

+			params->u.mem.size -= SZ_1M;
+
 		params = tag_next (params);
 	}
 }