Re: [PATCH v4 4/4] ram: Document migration ram flags

[Eric Blake]

On Fri, Feb 10, 2023 at 12:37:30AM +0100, Juan Quintela wrote:
> 0x80 is RAM_SAVE_FLAG_HOOK, it is in qemu-file now.
> Bigger usable flag is 0x200, noticing that.
> We can reuse RAM_SAVe_FLAG_FULL.

SAVE

> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  migration/ram.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 32fab7b5ee..3648cfc357 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -67,22 +67,26 @@
>  /***********************************************************/
>  /* ram save/restore */
>  
> -/* RAM_SAVE_FLAG_ZERO used to be named RAM_SAVE_FLAG_COMPRESS, it
> +/*
> + * RAM_SAVE_FLAG_ZERO used to be named RAM_SAVE_FLAG_COMPRESS, it
>   * worked for pages that where filled with the same char.  We switched

As long as you're in the area,

s/where/were/

>   * it to only search for the zero value.  And to avoid confusion with
>   * RAM_SSAVE_FLAG_COMPRESS_PAGE just rename it.

s/SSAVE/SAVE/

>   */
> -
> -#define RAM_SAVE_FLAG_FULL     0x01 /* Obsolete, not used anymore */
> +/*
> + * RAM_SAVE_FLAG_FULL was obsoleted in 2009, it can be reused now
> + */
> +#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
> -/* 0x80 is reserved in migration.h start with 0x100 next */
> +/* 0x80 is reserved in qemu-file.h for RAM_SAVE_FLAG_HOOK */
>  #define RAM_SAVE_FLAG_COMPRESS_PAGE    0x100
>  #define RAM_SAVE_FLAG_MULTIFD_SYNC     0x200
> +/* We can't use any flag that is bigger than 0x200 */

Spelling fixes are trivial; feel free to add:

Reviewed-by: Eric Blake <eblake@redhat.com>


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org