Re: [PATCH v2 07/11] scsi-disk: allow truncated MODE SELECT requests

[Paolo Bonzini]

On 4/24/22 18:49, Mark Cave-Ayland wrote:
> According to [1] this truncated request is accepted on real hardware whereas in
> QEMU it generates an INVALID_PARAM_LEN sense code which causes A/UX to get stuck
> in a loop retrying the command in an attempt to succeed.

That's for MODE SENSE, not MODE SELECT.

Truncated MODE SELECT is a bit more iffy, so I'd rather have a quirk for 
this as well.

Paolo

> Alter the mode page request length check so that truncated requests are allowed
> as per real hardware, adding a trace event to enable the condition to be 
> detected.
>
> [1]https://68kmla.org/bb/index.php?threads/scsi2sd-project-anyone-interested.29040/page-7#post-316444
>
> Signed-off-by: Mark Cave-Ayland<mark.cave-ayland@ilande.co.uk>
> ---
>   hw/scsi/scsi-disk.c  | 2 +-
>   hw/scsi/trace-events | 1 +
>   2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index 71fdf132c1..c657e4f5da 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -1525,7 +1525,7 @@ static int mode_select_pages(SCSIDiskReq *r, uint8_t *p, 
> int len, bool change)
>               goto invalid_param;
>           }
>           if (page_len > len) {
> -            goto invalid_param_len;
> +            trace_scsi_disk_mode_select_page_truncated(page, page_len, len);
>           }