[U-Boot] [PATCH] hwconfig: Utilize getenv_f before relocation to allow for larger buffer

[Kumar Gala]

Since we use hwconfig in cases before relocation (like getting DDR
params on FSL PPC systems), we can have strings he exceed the early
small (32 byte) buffer size that getenv will handle.

So we explicitly allocate our own buffer on the stack and use if to
handle getting the hwconfig env string.  We currently utilize a string
length of 128 bytes.

This allows us to get rid of boot messages like:

env_buf too small [32]

Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
---
 common/hwconfig.c |   21 ++++++++++++++++++++-
 1 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/common/hwconfig.c b/common/hwconfig.c
index 1f9f4a0..8f7a40f 100644
--- a/common/hwconfig.c
+++ b/common/hwconfig.c
@@ -26,6 +26,8 @@
 #define min(a, b) (((a) < (b)) ? (a) : (b))
 #endif /* HWCONFIG_TEST */
 
+DECLARE_GLOBAL_DATA_PTR;
+
 static const char *hwconfig_parse(const char *opts, size_t maxlen,
 				  const char *opt, char *stopchs, char eqch,
 				  size_t *arglen)
@@ -69,9 +71,26 @@ next:
 const char *cpu_hwconfig __attribute__((weak));
 const char *board_hwconfig __attribute__((weak));
 
+#define CONFIG_SYS_HWCONFIG_PRE_RELOC_BUF_SIZE	128
+
 static const char *__hwconfig(const char *opt, size_t *arglen)
 {
-	const char *env_hwconfig = getenv("hwconfig");
+	const char *env_hwconfig = NULL;
+	char buf[CONFIG_SYS_HWCONFIG_PRE_RELOC_BUF_SIZE];
+
+	if (gd->flags & GD_FLG_ENV_READY) {
+		env_hwconfig = getenv("hwconfig");
+	} else {
+		/*
+		 * Use our own on stack based buffer before relocation to allow
+		 * accesing longer hwconfig strings that might be in the
+		 * environment before we've relocated.  This is pretty fragile
+		 * on both the use of stack and if the buffer is big enough.
+		 * However we will get a warning from getenv_f for the later.
+		 */
+		if ((getenv_f("hwconfig", buf, sizeof(buf))) > 0)
+			env_hwconfig = buf;
+	}
 
 	if (env_hwconfig)
 		return hwconfig_parse(env_hwconfig, strlen(env_hwconfig),
-- 
1.7.2.3