Hi Alex,
On 02/06/2026 20:14, Alex Williamson wrote:
On Tue, 2 Jun 2026 17:50:04 +0100 Matt Evans mattev@meta.com wrote:
On 29/05/2026 00:14, Alex Williamson wrote:
On Wed, 27 May 2026 03:23:12 -0700 Matt Evans mattev@meta.com wrote:
uint32_t old_attr = priv->memattr;if (flags & VFIO_DEVICE_FEATURE_SET) {switch(db_attr.memattr) {case VFIO_DEVICE_FEATURE_DMA_BUF_MEMATTR_NC:case VFIO_DEVICE_FEATURE_DMA_BUF_MEMATTR_WC:priv->memattr = db_attr.memattr;break;default:ret = -ENOTSUPP;-EINVAL
I'd like to push back on this one; ENOTSUPP distinguishes trying to use a wild attribute value from all manner of other screwups such as trying to GET (with it no longer supported), passing an fd that isn't a DMABUF, etc.
I'm not wed to the value ENOTSUPP, just something distinctive versus the other errors userspace might see, and that value seems appropriate.
It needs to be a uAPI errno though, aiui ENOTSUPP is an internal NFS errno. How about EOPNOTSUPP? Thanks,
Ew, right! TIL, and it's caught by checkpatch too (which I fastidiously run but still missed this somehow...) :( "ENOTSUPP is not a standard error code and should be avoided in new patches. EOPNOTSUPP should be used instead."
Fixed.
Thanks,
Matt