Alex Williamson <alex.williamson@xxxxxxxxxx> writes: > At least for KVM the kernel fix is the addition of the vfio driver which > gives us a non-sysfs way to do this. If this problem was found a few > years later and we were ready to make the switch I'd support just > removing these resource files. In the meantime we have userspace that > depends on this interface, so I'm open to suggestions how to fix it. I am puzzled by a couple of things in this discussion: 1) do you seriously mean that a userspace application (any, not just udevadm or qemu or whatever) should be able to read and write these registers while the device is owned by a driver? How is that ever going to work? 2) is it really so that a device can be so fundamentally screwed up by reading some registers, that a later driver probe cannot properly reinitialize it? I would have thought that the solution to all this was to return -EINVAL on any attemt to read or write these files while a driver is bound to the device. If userspace is going to use the API, then the application better unbind any driver first. Or? Am I missing something here? > If we want to blacklist this specific device, that's fine, but as others > have pointed out it's really a class problem. Perhaps we report 1 byte > extra for the file length where EOF-1 is an enable byte? Is there > anything else in file ops that we could use to make it slightly more > complicated than open(), read() to access the device? Thanks, If there really are devices which cannot handle reading at all, and cannot be reset to a sane state by later driver initialization, then a blacklist could be added for those devices. This should not be a common problem. Bjørn -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
