Re: [patch][rfc]flattened device tree: Passing a dtb (blob) to Linux.

[Jimi Xenidis <jimix@watson.ibm.com>]

On Apr 13, 2006, at 7:12 PM, Benjamin Herrenschmidt wrote:
>
> We should make lmb_reserve() of redudant/overlapping entries become
> harmless I think.

Hmm.. I think it would be worthy of a warning, no?

> We need to be backward compatible with earlier blobs
> that do contain themselves in the reserve map

Do you think it is possible that the blob may have a single  
reservation that includes the blob but is larger? if not then we  
could simply do..
--
diff -r eb0990a251a9 arch/powerpc/kernel/prom.c
--- a/arch/powerpc/kernel/prom.c	Thu Mar 30 22:05:40 2006 -0500
+++ b/arch/powerpc/kernel/prom.c	Fri Apr 14 08:44:10 2006 -0400
@@ -1129,9 +1129,17 @@ static void __init early_reserve_mem(voi
{
	u64 base, size;
	u64 *reserve_map;
+	unsigned long self_base;
+	unsigned long self_size;
	reserve_map = (u64 *)(((unsigned long)initial_boot_params) +
					initial_boot_params->off_mem_rsvmap);
+
+	/* before we do anything, lets reserve the dt blob */
+	self_base = __pa((unsigned long)initial_boot_params);
+	self_size = initial_boot_params->totalsize;
+	lmb_reserve(self_base, self_size);
+
#ifdef CONFIG_PPC32
	/*
	 * Handle the case where we might be booting from an old kexec
@@ -1146,6 +1154,9 @@ static void __init early_reserve_mem(voi
			size_32 = *(reserve_map_32++);
			if (size_32 == 0)
				break;
+			/* skip if the reservation is for the blob */
+			if (base_32 == self_base && size_32 == self_size)
+				continue;
			DBG("reserving: %x -> %x\n", base_32, size_32);
			lmb_reserve(base_32, size_32);
		}
@@ -1157,6 +1168,9 @@ static void __init early_reserve_mem(voi
		size = *(reserve_map++);
		if (size == 0)
			break;
+		/* skip if the reservation is for the blob */
+		if (base == self_base && size == self_size)
+			continue;
		DBG("reserving: %llx -> %llx\n", base, size);
		lmb_reserve(base, size);
	}