diff options
Diffstat (limited to 'Documentation/s390')
| -rw-r--r-- | Documentation/s390/vfio-ccw.rst | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/s390/vfio-ccw.rst b/Documentation/s390/vfio-ccw.rst index fca9c4f5bd9c..23e7d136f8b4 100644 --- a/Documentation/s390/vfio-ccw.rst +++ b/Documentation/s390/vfio-ccw.rst @@ -335,6 +335,12 @@ device. The current code allows the guest to start channel programs via START SUBCHANNEL, and to issue HALT SUBCHANNEL and CLEAR SUBCHANNEL. +Currently all channel programs are prefetched, regardless of the +p-bit setting in the ORB. As a result, self modifying channel +programs are not supported. For this reason, IPL has to be handled as +a special case by a userspace/guest program; this has been implemented +in QEMU's s390-ccw bios as of QEMU 4.1. + vfio-ccw supports classic (command mode) channel I/O only. Transport mode (HPF) is not supported. |