[U-Boot] [PATCH 02/16] arch/arm/lib/bootm.c: Optionally use existing atags

Pali Rohár
2011-12-17T17:03:04Z

This patch adapts the bootm command so that it can use an existing atags command
set up by a previous bootloader. If the environment variable "atagaddr" is unset,
bootm behaves as normal. If "atagaddr" is set, bootm will use atags address from
environment variable and also append new boot args (if specified in u-boot). For
example, if a previous boot loader already set up the atags struct at 0x80000100:

setenv atagaddr 0x80000100; bootm 0x80008000

Signed-off-by: Pali Roh?r <pali.rohar@gmail.com>
---
README | 2 ++
arch/arm/lib/bootm.c | 27 +++++++++++++++++++++++++--
2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/README b/README
index ff72e47..3dd5a97 100644
--- a/README
+++ b/README
@@ -3564,6 +3564,8 @@ Some configuration options can be set using Environment Variables.

List of environment variables (most likely not complete):

+ atagaddr - bootm will use ATAGs struct from specified address (arm only)
+
baudrate - see CONFIG_BAUDRATE

bootdelay - see CONFIG_BOOTDELAY
diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index 802e833..4a3c423 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -125,12 +125,24 @@ int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
debug ("## Transferring control to Linux (at address %08lx) ...\n",
(ulong) kernel_entry);

+ s = getenv ("atagaddr");
+ if (s) {
+ bd->bi_boot_params = simple_strtoul(s, NULL, 16);
+ printf("Using existing atags at %#x\n", bd->bi_boot_params);
+
+ params = (struct tag *) bd->bi_boot_params;
+ while (params->hdr.size > 0)
+ params = tag_next (params);
+ } else {
#if defined (CONFIG_SETUP_MEMORY_TAGS) || \
defined (CONFIG_CMDLINE_TAG) || \
defined (CONFIG_INITRD_TAG) || \
defined (CONFIG_SERIAL_TAG) || \
defined (CONFIG_REVISION_TAG)
- setup_start_tag (bd);
+ setup_start_tag (bd);
+ }
+#endif
+
#ifdef CONFIG_SERIAL_TAG
setup_serial_tag (&params);
#endif
@@ -147,8 +159,19 @@ int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
if (images->rd_start && images->rd_end)
setup_initrd_tag (bd, images->rd_start, images->rd_end);
#endif
- setup_end_tag(bd);
+
+ if (s) {
+ if (params->hdr.size > 0)
+ setup_end_tag(bd);
+ } else {
+#if defined (CONFIG_SETUP_MEMORY_TAGS) || \
+ defined (CONFIG_CMDLINE_TAG) || \
+ defined (CONFIG_INITRD_TAG) || \
+ defined (CONFIG_SERIAL_TAG) || \
+ defined (CONFIG_REVISION_TAG)
+ setup_end_tag(bd);
#endif
+ }

announce_and_cleanup();

--
1.7.5.4