Re: [Qemu-devel] [PATCH v4 5/5] atapi: GESN: implement 'media' subcommand

[Kevin Wolf <kwolf@redhat.com>]

Am 12.04.2011 16:09, schrieb Amit Shah:
> Implement the 'media' sub-command of the GET_EVENT_STATUS_NOTIFICATION
> command.  This helps us report tray open, tray closed, no media, media
> present states to the guest.
> 
> Newer Linux kernels (2.6.38+) rely on this command to revalidate discs
> after media change.
> 
> This patch also sends out tray open/closed status to the guest driver
> when requested e.g. via the CDROM_DRIVE_STATUS ioctl (thanks Markus).
> Without such notification, the guest and qemu's tray open/close status
> was frequently out of sync, causing installers like Anaconda detecting
> no disc instead of tray open, confusing them terribly.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/ide/core.c     |  109 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>  hw/ide/internal.h |    6 +++
>  2 files changed, 110 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index dafc049..209d8e6 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1084,6 +1084,49 @@ static int ide_dvd_read_structure(IDEState *s, int format,
>      }
>  }
>  
> +static unsigned int event_status_media(IDEState *s,
> +                                       uint8_t *buf,
> +                                       unsigned int max_len)
> +{
> +    enum media_event_code {
> +        no_change = 0,       /* Status unchanged */
> +        eject_requested,     /* received a request from user to eject */
> +        new_media,           /* new media inserted and ready for access */
> +        media_removal,       /* only for media changers */
> +        media_changed,       /* only for media changers */
> +        bg_format_completed, /* MRW or DVD+RW b/g format completed */
> +        bg_format_restarted, /* MRW or DVD+RW b/g format restarted */
> +    };
> +    enum media_status {
> +        tray_open = 1,
> +        media_present = 2,
> +    };
> +    uint8_t event_code, media_status;
> +
> +    media_status = 0;
> +    if (s->bs->tray_open) {
> +        media_status = tray_open;
> +    } else if (bdrv_is_inserted(s->bs)) {
> +        media_status = media_present;
> +    }
> +
> +    /* Event notification descriptor */
> +    event_code = no_change;
> +    if (media_status != tray_open && s->events.new_media) {
> +        event_code = new_media;
> +        s->events.new_media = false;
> +    }
> +
> +    buf[4] = event_code;
> +    buf[5] = media_status;
> +
> +    /* These fields are reserved, just clear them. */
> +    buf[6] = 0;
> +    buf[7] = 0;
> +
> +    return 8; /* We wrote to 4 extra bytes from the header */
> +}
> +
>  static void handle_get_event_status_notification(IDEState *s,
>                                                   uint8_t *buf,
>                                                   const uint8_t *packet)
> @@ -1104,6 +1147,26 @@ static void handle_get_event_status_notification(IDEState *s,
>          uint8_t supported_events;
>      } __attribute((packed)) *gesn_event_header;
>  
> +    enum notification_class_request_type {
> +        reserved1 = 1 << 0,
> +        operational_change = 1 << 1,
> +        power_management = 1 << 2,
> +        external_request = 1 << 3,
> +        media = 1 << 4,
> +        multi_host = 1 << 5,
> +        device_busy = 1 << 6,
> +        reserved2 = 1 << 7,
> +    };
> +    enum event_notification_class_field {
> +        enc_no_events = 0,
> +        enc_operational_change,
> +        enc_power_management,
> +        enc_external_request,
> +        enc_media,
> +        enc_multiple_hosts,
> +        enc_device_busy,
> +        enc_reserved,
> +    };
>      unsigned int max_len, used_len;
>  
>      gesn_cdb = (void *)packet;
> @@ -1121,12 +1184,25 @@ static void handle_get_event_status_notification(IDEState *s,
>  
>      /* polling mode operation */
>  
> -    /* We don't support any event class (yet). */
> -    gesn_event_header->supported_events = 0;
> -
> -    gesn_event_header->notification_class = 0x80; /* No event available */
> -    used_len = sizeof(*gesn_event_header);
> +    /*
> +     * These are the supported events.
> +     *
> +     * We currently only support requests of the 'media' type.
> +     */
> +    gesn_event_header->supported_events = media;
>  
> +    /*
> +     * Responses to requests are to be based on request priority.  The
> +     * notification_class_request_type enum above specifies the
> +     * priority: upper elements are higher prio than lower ones.
> +     */
> +    if (gesn_cdb->class & media) {
> +        gesn_event_header->notification_class |= enc_media;

Am I missing where this field is initialized or should it be = instead
of |= ?

The rest of the series looks good, but I have seen this code by far too
often now, so maybe someone else should take over and find the remaining
bugs that I'm missing now...

Kevin