Messages in this thread | | | Subject | Re: [PATCH v10 01/16] s390/vfio-ap: add version vfio_ap module | From | Tony Krowiak <> | Date | Wed, 26 Aug 2020 10:49:47 -0400 |
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On 8/25/20 6:04 AM, Cornelia Huck wrote: > On Fri, 21 Aug 2020 15:56:01 -0400 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >> Let's set a version for the vfio_ap module so that automated regression >> tests can determine whether dynamic configuration tests can be run or >> not. >> >> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> >> --- >> drivers/s390/crypto/vfio_ap_drv.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c >> index be2520cc010b..f4ceb380dd61 100644 >> --- a/drivers/s390/crypto/vfio_ap_drv.c >> +++ b/drivers/s390/crypto/vfio_ap_drv.c >> @@ -17,10 +17,12 @@ >> >> #define VFIO_AP_ROOT_NAME "vfio_ap" >> #define VFIO_AP_DEV_NAME "matrix" >> +#define VFIO_AP_MODULE_VERSION "1.2.0" >> >> MODULE_AUTHOR("IBM Corporation"); >> MODULE_DESCRIPTION("VFIO AP device driver, Copyright IBM Corp. 2018"); >> MODULE_LICENSE("GPL v2"); >> +MODULE_VERSION(VFIO_AP_MODULE_VERSION); >> >> static struct ap_driver vfio_ap_drv; >> > Setting a version manually has some drawbacks: > - tools wanting to check for capabilities need to keep track which > versions support which features > - you need to remember to actually bump the version when adding a new, > visible feature > (- selective downstream backports may get into a pickle, but that's > arguably not your problem) > > Is there no way for a tool to figure out whether this is supported? > E.g., via existence of a sysfs file, or via a known error that will > occur. If not, it's maybe better to expose known capabilities via a > generic interface.
This patch series introduces a new mediated device sysfs attribute, guest_matrix, so the automated tests could check for the existence of that interface. The problem I have with that is it will work for this version of the vfio_ap device driver - which may be all that is ever needed - but does not account for future enhancements which may need to be detected by tooling or automated tests. It seems to me that regardless of how a tool detects whether a feature is supported or not, it will have to keep track of that somehow.
Can you provide more details about this generic interface of which you speak?
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