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virtio/s390: deprecate old transport 

There only ever have been two host implementations of the old
s390-virtio (pre-ccw) transport: the experimental kuli userspace,
and qemu. As qemu switched its default to ccw with 2.4 (with most
users having used ccw well before that) and removed the old transport
entirely in 2.6, s390-virtio probably hasn't been in active use for
quite some time and is therefore likely to bitrot.

Let's start the slow march towards removing the code by deprecating
it.

Note that this also deprecates the early virtio console code, which
has been causing trouble in the guest without being wired up in any
relevant hypervisor code.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Reviewed-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Cornelia Huck 2016-07-07 17:07:57 +02:00 committed by Michael S. Tsirkin
parent 2ab0d56aad
commit 3b2fbb3f06
3 changed files with 20 additions and 1 deletions
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13
arch/s390/Kconfig
View File

@ -871,4 +871,17 @@ config S390_GUEST
Select this option if you want to run the kernel as a guest under
the KVM hypervisor.
config S390_GUEST_OLD_TRANSPORT
def_bool y
prompt "Guest support for old s390 virtio transport (DEPRECATED)"
depends on S390_GUEST
help
Enable this option to add support for the old s390-virtio
transport (i.e. virtio devices NOT based on virtio-ccw). This
type of virtio devices is only available on the experimental
kuli userspace or with old (< 2.6) qemu. If you are running
with a modern version of qemu (which supports virtio-ccw since
1.4 and uses it by default since version 2.4), you probably won't
need this.
endmenu

6
drivers/s390/virtio/Makefile
View File

@ -6,4 +6,8 @@
# it under the terms of the GNU General Public License (version 2 only)
# as published by the Free Software Foundation.
obj-$(CONFIG_S390_GUEST) += kvm_virtio.o virtio_ccw.o
s390-virtio-objs := virtio_ccw.o
ifdef CONFIG_S390_GUEST_OLD_TRANSPORT
s390-virtio-objs += kvm_virtio.o
endif
obj-$(CONFIG_S390_GUEST) += $(s390-virtio-objs)

2
drivers/s390/virtio/kvm_virtio.c
View File

@ -458,6 +458,8 @@ static int __init kvm_devices_init(void)
if (test_devices_support(total_memory_size) < 0)
return -ENODEV;
pr_warn("The s390-virtio transport is deprecated. Please switch to a modern host providing virtio-ccw.\n");
rc = vmem_add_mapping(total_memory_size, PAGE_SIZE);
if (rc)
return rc;