bootm: Support string substitution in bootargs

In some cases it is necessary to pass parameters to Linux so that it will
boot correctly. For example, the rootdev parameter is often used to
specify the root device. However the root device may change depending on
whence U-Boot loads the kernel. At present it is necessary to build up
the command line by adding device strings to it one by one.

It is often more convenient to provide a template for bootargs, with
U-Boot doing the substitution from other environment variables.

Add a way to substitute strings in the bootargs variable. This allows
things like "rootdev=${rootdev}" to be used in bootargs, with the
${rootdev} substitution providing the UUID of the root device.

For example, to substitute the GUID of the kernel partition:

  setenv bootargs "console=/dev/ttyS0 rootdev=${uuid}/PARTNROFF=1
		kern_guid=${uuid}"
  part uuid mmc 2:2 uuid
  bootm

This is particularly useful when the command line from another place. For
example, Chrome OS stores the command line next to the kernel itself. It
depends on the kernel version being used as well as the hardware features,
so it is extremely difficult to devise a U-Boot script that works on all
boards and kernel versions. With this feature, the command line can be
read from disk and used directly, with a few substitutions set up.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 109 insertions, 5 deletions

diff --git a/test/bootm.c b/test/bootm.c
index d0b29441d6..92dc2b6e17 100644
--- a/test/bootm.c
+++ b/test/bootm.c
@@ -116,22 +116,126 @@ static int bootm_test_silent(struct unit_test_state *uts)
 }
 BOOTM_TEST(bootm_test_silent, 0);
 
+/* Test substitution processing */
+static int bootm_test_subst(struct unit_test_state *uts)
+{
+	char buf[BUF_SIZE];
+
+	/* try with an unset variable */
+	ut_assertok(env_set("var", NULL));
+	strcpy(buf, "some${var}thing");
+	ut_assertok(bootm_process_cmdline(buf, BUF_SIZE, BOOTM_CL_SUBST));
+	ut_asserteq_str("something", buf);
+
+	/* Replace with shorter string */
+	ut_assertok(env_set("var", "bb"));
+	strcpy(buf, "some${var}thing");
+	ut_assertok(bootm_process_cmdline(buf, BUF_SIZE, BOOTM_CL_SUBST));
+	ut_asserteq_str("somebbthing", buf);
+
+	/* Replace with same-length string */
+	ut_assertok(env_set("var", "abc"));
+	strcpy(buf, "some${var}thing");
+	ut_assertok(bootm_process_cmdline(buf, BUF_SIZE, BOOTM_CL_SUBST));
+	ut_asserteq_str("someabcthing", buf);
+
+	/* Replace with longer string */
+	ut_assertok(env_set("var", "abcde"));
+	strcpy(buf, "some${var}thing");
+	ut_assertok(bootm_process_cmdline(buf, BUF_SIZE, BOOTM_CL_SUBST));
+	ut_asserteq_str("someabcdething", buf);
+
+	/* Check it is case sensitive */
+	ut_assertok(env_set("VAR", NULL));
+	strcpy(buf, "some${VAR}thing");
+	ut_assertok(bootm_process_cmdline(buf, BUF_SIZE, BOOTM_CL_SUBST));
+	ut_asserteq_str("something", buf);
+
+	/* Check too long - need 12 bytes for each string */
+	strcpy(buf, "some${var}thing");
+	ut_asserteq(-ENOSPC,
+		    bootm_process_cmdline(buf, 12 * 2 - 1, BOOTM_CL_SUBST));
+
+	/* Check just enough space */
+	strcpy(buf, "some${var}thing");
+	ut_assertok(bootm_process_cmdline(buf, 16 * 2, BOOTM_CL_SUBST));
+	ut_asserteq_str("someabcdething", buf);
+
+	/*
+	 * Check the substition string being too long. This results in a string
+	 * of 12 (13 bytes). We need enough space for that plus the original
+	 * "a${var}c" string of 9 bytes. So 12 + 9 = 21 bytes.
+	 */
+	ut_assertok(env_set("var", "1234567890"));
+	strcpy(buf, "a${var}c");
+	ut_asserteq(-ENOSPC, bootm_process_cmdline(buf, 21, BOOTM_CL_SUBST));
+
+	strcpy(buf, "a${var}c");
+	ut_asserteq(0, bootm_process_cmdline(buf, 22, BOOTM_CL_SUBST));
+
+	/* Check multiple substitutions */
+	ut_assertok(env_set("var", "abc"));
+	strcpy(buf, "some${var}thing${bvar}else");
+	ut_asserteq(0, bootm_process_cmdline(buf, BUF_SIZE, BOOTM_CL_SUBST));
+	ut_asserteq_str("someabcthingelse", buf);
+
+	/* Check multiple substitutions */
+	ut_assertok(env_set("bvar", "123"));
+	strcpy(buf, "some${var}thing${bvar}else");
+	ut_asserteq(0, bootm_process_cmdline(buf, BUF_SIZE, BOOTM_CL_SUBST));
+	ut_asserteq_str("someabcthing123else", buf);
+
+	return 0;
+}
+BOOTM_TEST(bootm_test_subst, 0);
+
 /* Test silent processing in the bootargs variable */
 static int bootm_test_silent_var(struct unit_test_state *uts)
 {
 	env_set("bootargs", NULL);
-	env_set("silent_linux", NULL);
-	ut_assertok(bootm_process_cmdline_env(BOOTM_CL_SILENT));
+	ut_assertok(bootm_process_cmdline_env(BOOTM_CL_SUBST));
 	ut_assertnull(env_get("bootargs"));
 
-	env_set("bootargs", CONSOLE_STR);
-	env_set("silent_linux", "yes");
+	ut_assertok(env_set("bootargs", "some${var}thing"));
+	ut_assertok(bootm_process_cmdline_env(BOOTM_CL_SUBST));
+	ut_asserteq_str("something", env_get("bootargs"));
+
+	return 0;
+}
+BOOTM_TEST(bootm_test_silent_var, 0);
+
+/* Test substitution processing in the bootargs variable */
+static int bootm_test_subst_var(struct unit_test_state *uts)
+{
+	env_set("bootargs", NULL);
 	ut_assertok(bootm_process_cmdline_env(BOOTM_CL_SILENT));
 	ut_asserteq_str("console=", env_get("bootargs"));
 
+	ut_assertok(env_set("var", "abc"));
+	ut_assertok(env_set("bootargs", "some${var}thing"));
+	ut_assertok(bootm_process_cmdline_env(BOOTM_CL_SILENT));
+	ut_asserteq_str("some${var}thing console=", env_get("bootargs"));
+
 	return 0;
 }
-BOOTM_TEST(bootm_test_silent_var, 0);
+BOOTM_TEST(bootm_test_subst_var, 0);
+
+/* Test substitution and silent console processing in the bootargs variable */
+static int bootm_test_subst_both(struct unit_test_state *uts)
+{
+	ut_assertok(env_set("silent_linux", "yes"));
+	env_set("bootargs", NULL);
+	ut_assertok(bootm_process_cmdline_env(BOOTM_CL_ALL));
+	ut_asserteq_str("console=", env_get("bootargs"));
+
+	ut_assertok(env_set("bootargs", "some${var}thing " CONSOLE_STR));
+	ut_assertok(env_set("var", "1234567890"));
+	ut_assertok(bootm_process_cmdline_env(BOOTM_CL_ALL));
+	ut_asserteq_str("some1234567890thing console=", env_get("bootargs"));
+
+	return 0;
+}
+BOOTM_TEST(bootm_test_subst_both, 0);
 
 int do_ut_bootm(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 {