Re: [Qemu-devel] [PATCH] docs/devel/migration.txt: keep functions consistent with the code

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Jay Zhou (jianjay.zhou@huawei.com) wrote:
> Since the commit 11808bb0c422134bf09119f4aa22c59b0ce84bf3 removed
> the put_buffer callback and using an iovec based write handler instead,
> the docs should be sync with the code too.
> 
> Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com>

Lets check with Dan (added to cc) since he wrote 11808bb;
it might be best just to rever to migration/qemu-file.h for an
explanation of each function.

Dave


> ---
>  docs/devel/migration.txt | 31 ++++++++++++++++++-------------
>  1 file changed, 18 insertions(+), 13 deletions(-)
> 
> diff --git a/docs/devel/migration.txt b/docs/devel/migration.txt
> index 4030703..e7b08c9 100644
> --- a/docs/devel/migration.txt
> +++ b/docs/devel/migration.txt
> @@ -52,26 +52,31 @@ QEMU uses a QEMUFile abstraction to be able to do migration.  Any type
>  of migration that wants to use QEMU infrastructure has to create a
>  QEMUFile with:
>  
> -QEMUFile *qemu_fopen_ops(void *opaque,
> -                         QEMUFilePutBufferFunc *put_buffer,
> -                         QEMUFileGetBufferFunc *get_buffer,
> -                         QEMUFileCloseFunc *close);
> +typedef struct QEMUFileOps {
> +    QEMUFileGetBufferFunc *get_buffer;
> +    QEMUFileCloseFunc *close;
> +    QEMUFileSetBlocking *set_blocking;
> +    QEMUFileWritevBufferFunc *writev_buffer;
> +    QEMURetPathFunc *get_return_path;
> +    QEMUFileShutdownFunc *shut_down;
> +} QEMUFileOps;
>  
> -The functions have the following functionality:
> +QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
>  
> -This function writes a chunk of data to a file at the given position.
> -The pos argument can be ignored if the file is only used for
> -streaming.  The handler should try to write all of the data it can.
> +The main functions of QEMUFileOps have the following functionality:
>  
> -typedef int (QEMUFilePutBufferFunc)(void *opaque, const uint8_t *buf,
> -                                    int64_t pos, int size);
> +This function writes an iovec to file. The handler must write all
> +of the data or return a negative errno value.
> +
> +typedef ssize_t (QEMUFileWritevBufferFunc)(void *opaque, struct iovec *iov,
> +                                           int iovcnt, int64_t pos);
>  
>  Read a chunk of data from a file at the given position.  The pos argument
>  can be ignored if the file is only be used for streaming.  The number of
>  bytes actually read should be returned.
>  
> -typedef int (QEMUFileGetBufferFunc)(void *opaque, uint8_t *buf,
> -                                    int64_t pos, int size);
> +typedef ssize_t (QEMUFileGetBufferFunc)(void *opaque, uint8_t *buf,
> +                                        int64_t pos, int size);
>  
>  Close a file and return an error code.
>  
> @@ -80,7 +85,7 @@ typedef int (QEMUFileCloseFunc)(void *opaque);
>  You can use any internal state that you need using the opaque void *
>  pointer that is passed to all functions.
>  
> -The important functions for us are put_buffer()/get_buffer() that
> +The important functions for us are writev_buffer()/get_buffer() that
>  allow to write/read a buffer into the QEMUFile.
>  
>  === How to save the state of one device ===
> -- 
> 1.8.3.1
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK