Re: [Qemu-devel] [PATCH 2/2] s390x/3270: handle writes of arbitrary length

[Cornelia Huck <cohuck@redhat.com>]

On Wed, 20 Sep 2017 19:23:14 +0200
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> The problem is, that the current implementation places unrealistic and
> arbitrary constraints on the length of writes to the device (that is the
> outbound requests), by asserting ccw.count being such that that even the
> worst case escaped payload will fit an  more or less arbitrary sized
> buffer. Actually on protocol level there is nothing to justify such
> a limitation.
> 
> Another strange thing is the return value which more or less reflects
> the size (written) after escaping instead of before escaping. This
> is strange, because this return value is used to calculate SCSW.count.

Didn't the Linux driver care about the count?

> 
> Let us teach 3270 how to deal with arbitrary long writes.
> 
> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
> Reported-by: Jason J . Herne <jjherne@linux.vnet.ibm.com>
> Tested-by: Jason J . Herne <jjherne@linux.vnet.ibm.com>
> ---
>  hw/char/terminal3270.c | 30 ++++++++++++++++++------------
>  1 file changed, 18 insertions(+), 12 deletions(-)

Looks good.