Christian Borntraeger wrote: > Am Dienstag 29 September 2009 19:18:09 schrieb Rusty Russell: >> PCI, lguest and s390 can all only support 256-byte configuration >> space. So, this giant field broke just about everyone. >> Unfortunately, removing it is not so simple: we don't want to break >> old userspace, but we're going to want to re-use that part of the >> struct. >> >> So, modern users can #define VIRTIO_BLK_IDENTIFY_DEPRECATED to indicate >> that they know it's no longer in the config struct, and can use any >> new features (all new features which add a configuration field will >> conflict with this deprecated one). > > > Since s390 never used the giant id field, it would be ok for us just delete it > (without the #define). IIRC kvm-userspace also never used that. Since qemu > upstream seems to use that field your way seems to be the only compatible... It seems simply retiring use of the VIRTIO_BLK_F_IDENTIFY binary value should be sufficient. The patch which implemented the cooperating logic in qemu was dropped due to the config space issue. So the case of a virtio_blk driver successfully negotiating the feature and trying to access the now depreciated structure area should effectively be a non-issue. The bit value can be reclaimed for reuse in the future when concern over any suspected usage falls into the noise. -john -- john.cooper@xxxxxxxxxx _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
