initramfs: debug detected compression method

This can greatly aid in narrowing down the real source of initramfs
problems such as failures related to the compression of the in-kernel
initramfs when an external initramfs is in use as well.  Existing errors
are ambiguous as to which initramfs is a problem and why.

[akpm@linux-foundation.org: use pr_debug()]
Signed-off-by: Daniel M. Weeks <dan@danweeks.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/decompress.c b/lib/decompress.c
index 4d1cd0397aab..86069d74c062 100644
--- a/lib/decompress.c
+++ b/lib/decompress.c
@@ -16,6 +16,7 @@
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/init.h>
+#include <linux/printk.h>
 
 #ifndef CONFIG_DECOMPRESS_GZIP
 # define gunzip NULL
@@ -61,6 +62,8 @@ decompress_fn __init decompress_method(const unsigned char *inbuf, int len,
         if (len < 2)
                 return NULL;    /* Need at least this much... */
 
+        pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
+
         for (cf = compressed_formats; cf->name; cf++) {
                 if (!memcmp(inbuf, cf->magic, 2))
                         break;