I ran into problems trying to boot the pandaboard, which I think is the same others reported on this list. After printing the pandaboard revision number execution simply stops. I traced the problem to an unaligned access in disk_register_partitions(). Barebox loads first sector of the disk in memory. The offset of the partition table is 446 (decimal) which causes the entire partition table to be unaligned.
Below is a simple patch. Though, I am not sure whether this is the right fix, because this would affect all arm platforms and I would expect that such a bug would be noted earlier. I fiddled a little with the alignment bit in the System Control Register, but without success. I have to admit that I don't yet fully understand the behaviour of this bit.
Does someone else have any ideas? Or is my patch acceptable?
Kind regards,
Fabian van der Werf
From f98e14b971e0269251d8694be4c7b0254a30bc52 Mon Sep 17 00:00:00 2001
From: Fabian van der Werf <fvanderwerf@xxxxxxxxx>
Date: Sat, 8 Oct 2011 13:34:30 +0200
Subject: [PATCH] Fixed unaligned access
---
drivers/ata/disk_drive.c | 15 ++++++++++-----
1 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/ata/disk_drive.c b/drivers/ata/disk_drive.c
index 14b5e66..6a5dc87 100644
--- a/drivers/ata/disk_drive.c
+++ b/drivers/ata/disk_drive.c
@@ -38,6 +38,7 @@
#include <malloc.h>
#include <common.h>
#include <block.h>
+#include <asm/unaligned.h>
/**
* Description of one partition table entry (D*S type)
@@ -97,25 +98,29 @@ static int disk_register_partitions(struct device_d *dev, struct partition_entry
int part_order[4] = {0, 1, 2, 3};
int i, rc;
char drive_name[16], partition_name[19];
+ u32 partition_start, partition_size;
/* TODO order the partitions */
for (i = 0; i < 4; i++) {
+ partition_start = get_unaligned(&table[part_order[i]].partition_start);
+ partition_size = get_unaligned(&table[part_order[i]].partition_size);
+
sprintf(drive_name, "%s%d", dev->name, dev->id);
sprintf(partition_name, "%s%d.%d", dev->name, dev->id, i);
- if (table[part_order[i]].partition_start != 0) {
+ if (partition_start != 0) {
#if 1
/* ignore partitions we can't handle due to 32 bit limits */
- if (table[part_order[i]].partition_start > 0x7fffff)
+ if (partition_start > 0x7fffff)
continue;
- if (table[part_order[i]].partition_size > 0x7fffff)
+ if (partition_size > 0x7fffff)
continue;
#endif
dev_dbg(dev, "Registering partition %s to drive %s\n",
partition_name, drive_name);
rc = devfs_add_partition(drive_name,
- table[part_order[i]].partition_start * SECTOR_SIZE,
- table[part_order[i]].partition_size * SECTOR_SIZE,
+ partition_start * SECTOR_SIZE,
+ partition_size * SECTOR_SIZE,
DEVFS_PARTITION_FIXED, partition_name);
if (rc != 0)
dev_err(dev, "Failed to register partition %s (%d)\n", partition_name, rc);
--
1.7.0.4
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