# HG changeset patch
# User hirofuchi
# Date 1393586078 -32400
# Node ID 34a08647f2e40d22960d8cb1de718a4391c15f3b
# Parent  93c3b58d3df2ea3f361779dad61240e9381f0bf4
make the requirement of CBLOCKSIZE clear

CBLOCKSIZE must be a power of 2. 1024 or 8192 should be possible, which is not equal to PAGESIZE.

diff --git a/xnbd_common.c b/trunk/xnbd_common.c
--- a/xnbd_common.c
+++ b/xnbd_common.c
@@ -25,6 +25,13 @@
 #include "xnbd_common.h"
 
 
+/*
+ * CBLOCKSIZE must be a power of 2, because bit operations are used in
+ * mmap_block_region functions. There is an assertion to check this in main()
+ * of xnbd-server.
+ *
+ * 1024 or 8192, which is different from the page size, is also possible, but not well tested.
+ **/
 const unsigned int CBLOCKSIZE = 4096;
 unsigned int PAGESIZE = 4096;
 
diff --git a/xnbd_server.c b/trunk/xnbd_server.c
--- a/xnbd_server.c
+++ b/xnbd_server.c
@@ -1060,10 +1060,9 @@
 	xnbd_initialize(&xnbd);
 
 
+	/* must be a power of 2 */
+	g_assert((CBLOCKSIZE & (CBLOCKSIZE - 1)) == 0);
 
-	PAGESIZE = (unsigned int) getpagesize();
-	if (CBLOCKSIZE % PAGESIZE != 0)
-		warn("CBLOCKSIZE %u PAGESIZE %u", CBLOCKSIZE, PAGESIZE);
 
 	if (xnbd.cmd == xnbd_cmd_proxy)
 		cachestat_initialize(DEFAULT_CACHESTAT_PATH, xnbd.nblocks);