[0/2] Automatically reserve the initrd

[0/2] Automatically reserve the initrd

[David Gibson]

Paulus, I believe these two patches are ready to be merged into the
for-2.6.22 branch of powerpc.git.  Together they make the kernel
automatically lmb_reserve() the space for the initrd image, removing
the requirement that the bootloader or zImage list the initrd's
address in the reserve map.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[PATCH 2/2] Automatically lmb_reserve() initrd

[David Gibson]

At present, when an initrd is passed to the kernel used flat device
tree properties, the memory the initrd occupies must also be reserved
in the flat tree's reserve map, or the kernel may overwrite it.  That
makes life more complicated than it could be for the bootwrapper.

This patch makes the kernel automatically reserve the initrd's space.
That in turn requires parsing the initrd parameters earlier than they
are currently, in early_init_dt_scan_chosen() instead of
check_for_initrd().

Signed-off-by: David Gibson <dwg@au1.ibm.com>
---

 arch/powerpc/kernel/prom.c         |   23 +++++++++++++++++++++++
 arch/powerpc/kernel/setup-common.c |   22 ++--------------------
 2 files changed, 25 insertions(+), 20 deletions(-)

Index: working-2.6/arch/powerpc/kernel/prom.c
===================================================================
--- working-2.6.orig/arch/powerpc/kernel/prom.c	2007-02-09 15:12:00.000000000 +1100
+++ working-2.6/arch/powerpc/kernel/prom.c	2007-02-09 15:14:27.000000000 +1100
@@ -719,6 +719,7 @@ static int __init early_init_dt_scan_cho
 					    const char *uname, int depth, void *data)
 {
 	unsigned long *lprop;
+	u32 *prop;
 	unsigned long l;
 	char *p;
 
@@ -760,6 +761,22 @@ static int __init early_init_dt_scan_cho
                crashk_res.end = crashk_res.start + *lprop - 1;
 #endif
 
+#ifdef CONFIG_BLK_DEV_INITRD
+	DBG("Looking for initrd properties... ");
+	prop = of_get_flat_dt_prop(node, "linux,initrd-start", &l);
+	if (prop) {
+		initrd_start = (unsigned long)__va(of_read_ulong(prop, l/4));
+		prop = of_get_flat_dt_prop(node, "linux,initrd-end", &l);
+		if (prop) {
+			initrd_end = (unsigned long)__va(of_read_ulong(prop, l/4));
+			initrd_below_start_ok = 1;
+		} else {
+			initrd_start = 0;
+		}
+	}
+	DBG("initrd_start=0x%lx  initrd_end=0x%lx\n", initrd_start, initrd_end);
+#endif /* CONFIG_BLK_DEV_INITRD */
+
 	/* Retreive command line */
  	p = of_get_flat_dt_prop(node, "bootargs", &l);
 	if (p != NULL && l > 0)
@@ -926,6 +943,12 @@ static void __init early_reserve_mem(voi
 	self_size = initial_boot_params->totalsize;
 	lmb_reserve(self_base, self_size);
 
+#ifdef CONFIG_BLK_DEV_INITRD
+	/* then reserve the initrd, if any */
+	if (initrd_start && (initrd_end > initrd_start))
+		lmb_reserve(__pa(initrd_start), initrd_end - initrd_start);
+#endif /* CONFIG_BLK_DEV_INITRD */
+
 #ifdef CONFIG_PPC32
 	/* 
 	 * Handle the case where we might be booting from an old kexec
Index: working-2.6/arch/powerpc/kernel/setup-common.c
===================================================================
--- working-2.6.orig/arch/powerpc/kernel/setup-common.c	2007-01-24 12:01:17.000000000 +1100
+++ working-2.6/arch/powerpc/kernel/setup-common.c	2007-02-09 15:15:15.000000000 +1100
@@ -304,26 +304,8 @@ struct seq_operations cpuinfo_op = {
 void __init check_for_initrd(void)
 {
 #ifdef CONFIG_BLK_DEV_INITRD
-	const unsigned int *prop;
-	int len;
-
-	DBG(" -> check_for_initrd()\n");
-
-	if (of_chosen) {
-		prop = get_property(of_chosen, "linux,initrd-start", &len);
-		if (prop != NULL) {
-			initrd_start = (unsigned long)
-				__va(of_read_ulong(prop, len / 4));
-			prop = get_property(of_chosen,
-					"linux,initrd-end", &len);
-			if (prop != NULL) {
-				initrd_end = (unsigned long)
-					__va(of_read_ulong(prop, len / 4));
-				initrd_below_start_ok = 1;
-			} else
-				initrd_start = 0;
-		}
-	}
+	DBG(" -> check_for_initrd()  initrd_start=0x%lx  initrd_end=0x%lx\n",
+	    initrd_start, initrd_end);
 
 	/* If we were passed an initrd, set the ROOT_DEV properly if the values
 	 * look sensible. If not, clear initrd reference.

[PATCH 1/2] powerpc: Allow duplicate lmb_reserve() calls

[David Gibson]

At present calling lmb_reserve() (and hence lmb_add_region()) twice
for exactly the same memory region will cause strange behaviour.

This makes life difficult when booting from a flat device tree with
memory reserve map.  Which regions are automatically reserved by the
kernel has changed over time, so it's quite possible a newer kernel
could attempt to auto-reserve a region which is also explicitly listed
in the device tree's reserve map, leading to trouble.

This patch avoids the problem by making lmb_reserve() ignore a call to
reserve a previously reserved region.  It also removes a now redundant
test designed to avoid one specific case of the problem noted above.

At present, this patch deals only with duplicate reservations of an
identical region.  Attempting to reserve two different, but
overlapping regions will still cause problems.  I might post another
patch later dealing with this case, but I'm avoiding it now since it
is substantially more complicated to deal with, less likely to occur
and more likely to indicate a genuine bug elsewhere if it does occur.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
---


 arch/powerpc/kernel/prom.c |    3 ---
 arch/powerpc/mm/lmb.c      |    4 ++++
 2 files changed, 4 insertions(+), 3 deletions(-)

Index: working-2.6/arch/powerpc/mm/lmb.c
===================================================================
--- working-2.6.orig/arch/powerpc/mm/lmb.c	2007-02-06 16:21:02.000000000 +1100
+++ working-2.6/arch/powerpc/mm/lmb.c	2007-02-06 16:22:32.000000000 +1100
@@ -146,6 +146,10 @@ static long __init lmb_add_region(struct
 		unsigned long rgnbase = rgn->region[i].base;
 		unsigned long rgnsize = rgn->region[i].size;
 
+		if ((rgnbase == base) && (rgnsize == size))
+			/* Already have this region, so we're done */
+			return 0;
+
 		adjacent = lmb_addrs_adjacent(base,size,rgnbase,rgnsize);
 		if ( adjacent > 0 ) {
 			rgn->region[i].base -= size;
Index: working-2.6/arch/powerpc/kernel/prom.c
===================================================================
--- working-2.6.orig/arch/powerpc/kernel/prom.c	2007-02-06 16:22:48.000000000 +1100
+++ working-2.6/arch/powerpc/kernel/prom.c	2007-02-06 16:22:57.000000000 +1100
@@ -954,9 +954,6 @@ 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);
 	}