[Qemu-devel] Re: [PATCH] floppy: save and restore DIR register

[Juan Quintela <quintela@redhat.com>]

Jason Wang <jasowang@redhat.com> wrote:
> We need to keep DIR register unchanged across migration, but currently it
> depends on the media_changed flags from block layer and we do not save/restore
> it which could let the guest driver think the floppy have changed after
> migration. To fix this, a new filed media_changed in FDrive strcutre was
> introduced in order to save and restore the it from block layer through
> pre_save/post_load callbacks.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  hw/fdc.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 46 insertions(+), 0 deletions(-)
>
> diff --git a/hw/fdc.c b/hw/fdc.c
> index 9fdbc75..8257d51 100644
> --- a/hw/fdc.c
> +++ b/hw/fdc.c
> @@ -36,6 +36,7 @@
>  #include "qdev-addr.h"
>  #include "blockdev.h"
>  #include "sysemu.h"
> +#include "block_int.h"
>  
>  /********************************************************/
>  /* debug Floppy devices */
> @@ -82,6 +83,7 @@ typedef struct FDrive {
>      uint8_t max_track;        /* Nb of tracks           */
>      uint16_t bps;             /* Bytes per sector       */
>      uint8_t ro;               /* Is read-only           */
> +    uint8_t media_changed;    /* Is media changed       */
>  } FDrive;
>  
>  static void fd_init(FDrive *drv)
> @@ -533,6 +535,42 @@ static CPUWriteMemoryFunc * const fdctrl_mem_write_strict[3] = {
>      NULL,
>  };
>  
> +static void fdrive_media_changed_pre_save(void *opaque)
> +{
> +    FDrive *drive = opaque;
> +
> +    drive->media_changed = drive->bs->media_changed;
> +}
> +
> +static int fdrive_media_changed_post_load(void *opaque, int version_id)
> +{
> +    FDrive *drive = opaque;
> +
> +    drive->bs->media_changed = drive->media_changed;

shouldn't this be something like:

if (!drive->bs)
   return 1;

drive->bs->media_changed = drive->media_changed.

???

Otherwise, we can can have troubles if floppy is not opened in the other side.


Rest of code looks nice, thanks.

Later, Juan.