On Fri, Oct 23, 2020 at 10:02:15AM +0200, Ulf Hansson wrote: > > > Is there no mechanism to support read-only PCIe/NVMe based storage > > > devices? > > > If that is the case, maybe it's simply better to not support the readonly > > > option > > > at all for SD express cards? > > > > > I think there's no mechanism to support read-only PCIe/NVMe based storage > > devices. > > I have looped in Christoph, maybe he can give us his opinion on this.
NVMe namespaces can have a bunch of 'write protection' modes advertised by the controller, which Linux respects. The controller in this case would be part of the SD-Card. IMHO it is a quality of implementation issue of the SD-Card/Controller to have the the write protection mode of the namespace(s) match that of the SD interface, and the SD card spec should talk about that if it doesn't already.
