mkbootimg: support longer kernel command lines
We can't simply increase the value of BOOT_ARGS_SIZE since that
would break past binary compatibility; the offset of 'id' would
change. This can cause serious problems with incremental OTA updates.
Instead, define a supplemental field which stores command line
information beyond the first 512 bytes. A value of 1024 was chosen
to keep the total size of struct boot_img_hdr under the smallest
page size of 2048 bytes.
Even if the extra_cmdline field is used, the original cmdline
field is still always NULL-terminated to avoid issues with older
bootloaders that haven't been updated.
Change-Id: I887e6f1db351a5b71a61e3a03363cf8856123d74
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
diff --git a/mkbootimg/mkbootimg.c b/mkbootimg/mkbootimg.c
index 34a879b..d598f03 100644
--- a/mkbootimg/mkbootimg.c
+++ b/mkbootimg/mkbootimg.c
@@ -114,6 +114,7 @@
unsigned ramdisk_offset = 0x01000000;
unsigned second_offset = 0x00f00000;
unsigned tags_offset = 0x00000100;
+ size_t cmdlen;
argc--;
argv++;
@@ -192,11 +193,19 @@
memcpy(hdr.magic, BOOT_MAGIC, BOOT_MAGIC_SIZE);
- if(strlen(cmdline) > (BOOT_ARGS_SIZE - 1)) {
+ cmdlen = strlen(cmdline);
+ if(cmdlen > (BOOT_ARGS_SIZE + BOOT_EXTRA_ARGS_SIZE - 2)) {
fprintf(stderr,"error: kernel commandline too large\n");
return 1;
}
- strcpy((char*)hdr.cmdline, cmdline);
+ /* Even if we need to use the supplemental field, ensure we
+ * are still NULL-terminated */
+ strncpy((char *)hdr.cmdline, cmdline, BOOT_ARGS_SIZE - 1);
+ hdr.cmdline[BOOT_ARGS_SIZE - 1] = '\0';
+ if (cmdlen >= (BOOT_ARGS_SIZE - 1)) {
+ cmdline += (BOOT_ARGS_SIZE - 1);
+ strncpy((char *)hdr.extra_cmdline, cmdline, BOOT_EXTRA_ARGS_SIZE);
+ }
kernel_data = load_file(kernel_fn, &hdr.kernel_size);
if(kernel_data == 0) {