Re: [Qemu-devel] [Qemu-block] [PATCH] atapi: allow 0 transfer bytes for read_cd command

[Kevin Wolf <kwolf@redhat.com>]

Am 18.08.2016 um 11:48 hat Hervé Poussineau geschrieben:
> This fixes Windows NT4 startup when a cdrom is inserted.
> 
> Fixes: 9ef2e93f9b1888c7d0deb4a105149138e6ad2e98
> Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>

Hm, which of the paths in cmd_read_cd() does this hit? Is it the one
that directly calls ide_atapi_cmd_ok() without doing anything?

I think adding NONDATA is okay, but we may need to add explicit
atapi_byte_count_limit() == 0 checks to those paths that do transfer
some data. At least at first sight I'm not sure that
ide_atapi_cmd_read() can handle this.

Kevin

>  hw/ide/atapi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
> index 6189675..63312f2 100644
> --- a/hw/ide/atapi.c
> +++ b/hw/ide/atapi.c
> @@ -1289,7 +1289,7 @@ static const struct AtapiCmd {
>      [ 0xad ] = { cmd_read_dvd_structure,            CHECK_READY },
>      [ 0xbb ] = { cmd_set_speed,                     NONDATA },
>      [ 0xbd ] = { cmd_mechanism_status,              0 },
> -    [ 0xbe ] = { cmd_read_cd,                       CHECK_READY },
> +    [ 0xbe ] = { cmd_read_cd,                       CHECK_READY | NONDATA },
>      /* [1] handler detects and reports not ready condition itself */
>  };