If user requests a hugepage size which is not supported by the system,
currently user gets an error message saying that the requested size
is not a valid system huge page size. In addition to this if we display
the valid hugepage sizes it will be convenient for the user to request
the right size next time.

Signed-off-by: Sarosh Arif <redacted>
---

--- a/usertools/dpdk-hugepages.py
+++ b/usertools/dpdk-hugepages.py

@@ -43,6 +43,12 @@ def is_numa():
     return os.path.exists('/sys/devices/system/node')
 
 
+def get_valid_page_sizes(path):
+    '''Extract valid hugepage sizes'''
+    dir = os.path.dirname(path)
+    pg_sizes = (d.split("-")[1] for d in os.listdir(dir))
+    return " ".join(pg_sizes)
+

 def get_hugepages(path):
     '''Read number of reserved pages'''
     with open(path + '/nr_hugepages') as nr_hugepages:

@@ -59,9 +65,8 @@ def set_hugepages(path, pages):
     except PermissionError:
         sys.exit('Permission denied: need to be root!')
     except FileNotFoundError:
-        filename = os.path.basename(path)
-        size = filename[10:]
-        sys.exit('{} is not a valid system huge page size'.format(size))
+        sys.exit("Invalid page size. Valid page sizes: {}".format(
+                get_valid_page_sizes(path)))