[Xen-changelog] [xen-unstable] blkif: Clarify units for 'sector'-sized blkif request params.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1243328514 -3600
# Node ID cc682927d12335d811e8ac07375123454baf6d84
# Parent  205b1badbcfdc5960dcf0e6c22c6e226da109cb4
blkif: Clarify units for 'sector'-sized blkif request params.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 xen/include/public/io/blkif.h |    7 +++++++
 1 files changed, 7 insertions(+)

diff -r 205b1badbcfd -r cc682927d123 xen/include/public/io/blkif.h
--- a/xen/include/public/io/blkif.h     Tue May 26 09:58:38 2009 +0100
+++ b/xen/include/public/io/blkif.h     Tue May 26 10:01:54 2009 +0100
@@ -84,6 +84,13 @@
  */
 #define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
 
+/* 
+ * NB. first_sect and last_sect in blkif_request_segment, as well as
+ * sector_number in blkif_request, are always expressed in 512-byte units.
+ * However they must be properly aligned to the real sector size of the
+ * physical disk, which is reported in the "sector-size" node in the backend
+ * xenbus info. Also the xenbus "sectors" node is expressed in 512-byte units.
+ */
 struct blkif_request_segment {
     grant_ref_t gref;        /* reference to I/O buffer frame        */
     /* @first_sect: first sector in frame to transfer (inclusive).   */

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog