Re: [PATCH v2 3/7] migration/ram: Move RAM_SAVE_FLAG* into ram.h

[Peter Xu <peterx@redhat.com>]

On Fri, Dec 06, 2024 at 12:10:46PM -0300, Fabiano Rosas wrote:
> > Wanna me to add a comment for that in this patch?
> 
> Yes, please.

When I did it, I also did a few other things:

  - Rearranged the comment section, put all things together
  - Remove RAM_SAVE_FLAG_ZERO directly
  - Reindents

The plan is to squash below diff in v3 post, feel free to comment before
that.

===8<===
From 593227f1b9e678418f5b99ac51525884fa0adfc6 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Fri, 6 Dec 2024 10:43:25 -0500
Subject: [PATCH] fixup! migration/ram: Move RAM_SAVE_FLAG* into ram.h

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/ram.h | 33 ++++++++++++++++++---------------
 migration/ram.c | 22 ++++++++++------------
 2 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/migration/ram.h b/migration/ram.h
index cfdcccd266..921c39a2c5 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -39,24 +39,27 @@
  * it to only search for the zero value.  And to avoid confusion with
  * RAM_SAVE_FLAG_COMPRESS_PAGE just rename it.
  *
- * RAM_SAVE_FLAG_FULL was obsoleted in 2009.
+ * RAM_SAVE_FLAG_FULL (0x01) was obsoleted in 2009.
  *
  * RAM_SAVE_FLAG_COMPRESS_PAGE (0x100) was removed in QEMU 9.1.
+ *
+ * RAM_SAVE_FLAG_HOOK is only used in RDMA. Whenever this is found in the
+ * data stream, the flags will be passed to rdma functions in the
+ * incoming-migration side.
+ *
+ * We can't use any flag that is bigger than 0x200, because the flags are
+ * always assumed to be encoded in a ramblock address offset, which is
+ * multiple of PAGE_SIZE.  Here it means QEMU supports migration with any
+ * architecture that has PAGE_SIZE>=1K (0x400).
  */
-#define RAM_SAVE_FLAG_FULL     0x01
-#define RAM_SAVE_FLAG_ZERO     0x02
-#define RAM_SAVE_FLAG_MEM_SIZE 0x04
-#define RAM_SAVE_FLAG_PAGE     0x08
-#define RAM_SAVE_FLAG_EOS      0x10
-#define RAM_SAVE_FLAG_CONTINUE 0x20
-#define RAM_SAVE_FLAG_XBZRLE   0x40
-/*
- * ONLY USED IN RDMA: Whenever this is found in the data stream, the flags
- * will be passed to rdma functions in the incoming-migration side.
- */
-#define RAM_SAVE_FLAG_HOOK     0x80
-#define RAM_SAVE_FLAG_MULTIFD_FLUSH    0x200
-/* We can't use any flag that is bigger than 0x200 */
+#define RAM_SAVE_FLAG_ZERO                    0x002
+#define RAM_SAVE_FLAG_MEM_SIZE                0x004
+#define RAM_SAVE_FLAG_PAGE                    0x008
+#define RAM_SAVE_FLAG_EOS                     0x010
+#define RAM_SAVE_FLAG_CONTINUE                0x020
+#define RAM_SAVE_FLAG_XBZRLE                  0x040
+#define RAM_SAVE_FLAG_HOOK                    0x080
+#define RAM_SAVE_FLAG_MULTIFD_FLUSH           0x200
 
 extern XBZRLECacheStats xbzrle_counters;
-- 
2.47.0


-- 
Peter Xu