Re: Using reblob to load another blob from ram

[Erik M. <er...@bi...>]

On Mon, May 01, 2006 at 06:22:16PM -0400, Dan wrote:
> Stefan Schmidt wrote:
> >On Fri, 2006-04-28 at 16:09, Erik Mouw wrote:
> >>You should be able to reblob the second stage loader (i.e.: blob-rest).
> >>It should be loaded at BLOB_RAM_BASE.
> >
> >JFYI: This did not work here. Perhaps this feature is disabled inside
> >the Motorola blob. I'm busy at the moment, but hopefully have some
> >time the next weekend for debugging this.
> 
> I observed that while BLOB loads and jumps to BLOB_RAM_BASE, the second 
> stage loader (blob-rest) is actually built to run at 
> BLOB_ABS_BASE_ADDR.   The reblob command should be [safely] copying the 
> second stage BLOB from BLOB_RAM_BASE to BLOB_ABS_BASE_ADDR and then 
> jumping there, but I guess it doesn't (not that I've checked in a while).

You nailed the problem, thanks. Here's the git patch to fix it (also
pushed to the repository). The target to use for reblob is/was
blob-chain.


Erik

diff-tree bd6e87da76478d39e134387edef68f2a0c766e5b (from 16ee5944280da198b1c569ddc8500797a8332d13)
Author: Erik Mouw <mo...@nl...>
Date:   Tue May 2 12:33:12 2006 +0200

    Recreate blob-chain target used for the "reblob" command.
    
    When overhauling the Makefile to include the second stage
    loader, I forgot to overhaul the chain loader as well. This
    patch recreats the blob-chain target. Also some minor cleanups
    in chain.S, we don't need to fiddle with the LEDs anymore.

diff --git a/src/blob/Makefile.am b/src/blob/Makefile.am
index 32151c5..18d3743 100644
--- a/src/blob/Makefile.am
+++ b/src/blob/Makefile.am
@@ -24,7 +24,9 @@ #
 bin_PROGRAMS	= \
 	blob-rest-elf32 \
 	blob-rest \
+	blob-chain-elf32 \
 	blob-elf32 \
+	blob-chain \
 	blob
 
 
@@ -188,6 +190,26 @@ blob: blob-elf32
 	$(OBJCOPY) $(OCFLAGS) $< $@
 
 
+# ---- Blob-chain first stage loader for use with reblob -------------
+
+blob_chain_elf32_SOURCES	= \
+	chain.S
+
+blob_chain_elf32_DEPENDENCIES = \
+	start-ld-script \
+	blob-rest-piggy.o
+
+blob_chain_elf32_LDFLAGS = \
+	-static -nostdlib \
+	-Wl,-T,${srcdir}/start-ld-script \
+	-Wl,-Map,blob-chain-elf32.map
+
+blob_chain_SOURCES =
+
+blob-chain: blob-chain-elf32
+	$(OBJCOPY) $(OCFLAGS) $< $@
+
+
 # ---- Automake administrativia --------------------------------------
 
 EXTRA_DIST	= \
diff --git a/src/blob/chain.S b/src/blob/chain.S
index 8b4d94c..a5550aa 100644
--- a/src/blob/chain.S
+++ b/src/blob/chain.S
@@ -45,20 +45,15 @@ _start:
 	sub	r0, pc, #8
 	str	r0, START
 
-#ifdef H3600
+	b	relocate
+
 	/* this is a hack to be able to chain load blob from
 	 * bootldr. bootldr checks if it can find the linux zImage
 	 * magic value at the ninth word of an image, so we just put
 	 * it there.
 	 */
-	b	led
 .org (_start + 9 * 4)
 	.word	0x016f2818
-led:
-#endif
-
-	/* init LED */
-	//bl	ledinit
 
 	/* assume that the CPU and the memory are already set up at
 	 * this point. also assume that interrupts are disabled, and if
@@ -92,12 +87,6 @@ copy_loop:
 	ble	copy_loop
 
 
-	/* turn off the LED. if it stays off it is an indication that
-	 * we didn't make it into the C code 
-	 */
-	//bl led_off
-
-
 	/* blob is copied to ram, so jump to it */
 	ldr	r0, BLOB_START
 	mov	pc, r0

-- 
----  Erik Mouw  ----  www.bitwizard.nl  ----  +31 15 2600 998  ----