On Thu, Dec 09, 2021 at 03:40:46PM -0800, Eric Biggers wrote: > On Thu, Dec 09, 2021 at 02:51:59PM -0800, Bart Van Assche wrote: > > On 12/7/21 5:35 PM, Eric Biggers wrote: > > > +What: /sys/block/<disk>/queue/crypto/modes/<mode> > > > +Date: December 2021 > > > +Contact: linux-block@xxxxxxxxxxxxxxx > > > +Description: > > > + [RO] For each crypto mode (i.e., encryption/decryption > > > + algorithm) the device supports with inline encryption, a file > > > + will exist at this location. It will contain a hexadecimal > > > + number that is a bitmask of the supported data unit sizes, in > > > + bytes, for that crypto mode. > > > + > > > + Currently, the crypto modes that may be supported are: > > > + > > > + * AES-256-XTS > > > + * AES-128-CBC-ESSIV > > > + * Adiantum > > > + > > > + For example, if a device supports AES-256-XTS inline encryption > > > + with data unit sizes of 512 and 4096 bytes, the file > > > + /sys/block/<disk>/queue/crypto/modes/AES-256-XTS will exist and > > > + will contain "0x1200". > > > > So a bitmask is used to combine multiple values into a single number? > > You could think of it that way, yes. > > > Has it been considered to report each value separately, e.g. 512\n4096\n > > instead of 0x1200\n? I think the former approach is more friendly for shell > > scripts. No multi-line outputs in sysfs please. If you have to do a "selection from an array", that is not how to do it. Look at the output of /sys/power/pm_test/ as one way you can do it if you have to choose one option from a list: $ cat /sys/power/pm_test [none] core processors platform devices freezer But I don't think that applies here, right? > I don't think that would be acceptable to the sysfs folks, as they only allow > one value per file. I suppose a bitmask could be viewed as unacceptable too, > but it seemed to make sense here, given that the data unit sizes are always > powers of 2, and the hardware reports them as bitmasks. > > Greg already reviewed this patch, but maybe he wasn't looking at this part. > > Greg, any opinion on the best way to report a set of power-of-2 values via > sysfs? A single hex value makes sense to me. thanks, greg k-h
