RE: nvme sanitize command

[Renaud Barbier <Renaud.Barbier@ametek.com>]

> Hi Renaud,
> 
> On 13.01.25 15:03, Renaud Barbier wrote:
> >> We do have ioctls on cdev in barebox, but we also have an actual
> >> erase operation, so I prefer we use that instead.
> >
> > Below the option for sanitize command:
> > # nvme sanitize --help
> > Usage: nvme sanitize <device> [OPTIONS]
> >
> > Send a sanitize command.
> >
> > Options:
> >   [  --no-dealloc, -d ]                 --- No deallocate after sanitize.
> >   [  --oipbp, -i ]                      --- Overwrite invert pattern between
> >                                             passes.
> >   [  --owpass=<NUM>, -n <NUM> ]         --- Overwrite pass count.
> >   [  --ause, -u ]                       --- Allow unrestricted sanitize exit.
> >   [  --sanact=<NUM>, -a <NUM> ]         --- Sanitize action.
> >   [  --ovrpat=<NUM>, -p <NUM> ]         --- Overwrite pattern.
> 
> Thanks, I had looked in nvme(1), but I should have looked in nvme-sanitize(1)
> instead.
> 
> > Note I am talking about sanitize operation that is  the whole device being
> erased i.e there is no start and end block to be specified.
> 
> So this is a single command that erases the whole device, but doesn't take
> block offsets/length as arguments? Do you know what value the erased data
> can have afterwards?

Indeed. No block offset/length as far as I can see from libnvme and nvme-cli Linux commands

I have added the erase entry point and ran the sanitize block erase command. This wiped out the whole device 
barebox@LS1046A RDB Board:/ md -s /dev/nvme0n1
00000000: 00000000 00000000 00000000 00000000                ................
00000010: 00000000 00000000 00000000 00000000                ................
00000020: 00000000 00000000 00000000 00000000                ................
00000030: 00000000 00000000 00000000 00000000                ................
00000040: 00000000 00000000 00000000 00000000                ................
00000050: 00000000 00000000 00000000 00000000                ................
...

Whatever the offset I give, I get 0.

> 
> > Using erase would limit sanitisation to erasing the whole media
> 
> Isn't this what you want? Erase the whole device at once?
Yes. My number one goal is reached.
There maybe a requirement for pattern writing with several passes later.

> Anyway, the erase command can be extended as needed to take offset/length
> or to change erasure type.
> 
> Currently erasing only part of the device is possible by adding calling erase on a
> partition (perhaps allocated via addpart).
> 
> > and no possibility to use the other options such as overwrite where a pattern
> and a number of pass is specified.
> 
> Generally, I prefer not to copy the Linux style of device-specific ioctl codes
> unless necessary.
> 
> For such very specific use cases, ioctl makes sense, yes.
> 
> cdev already supports ioctl, but block device doesn't, so the natural step
> would be to add struct block_device_ops::ioctl, which is called from struct
> block_device::cdev::ioctl.
> 
> I think we don't need that yet though, see below.
> 
> > Unless a way can be added to set features for sanitize.
> > At present, erase is all I need so I will add the erase entry point with the
> sanitisation action being NVME_SANITIZE_SANACT_START_BLOCK_ERASE as
> default.
> 
> How about you implement erase in nvme, but check that size arguments
> indeed describe the whole device: If it does, you do your sanitize operation
> and if it doesn't, return -ENOSYS.
> 
> Would that work for you?

Perfect. Thanks.
> 
> Cheers,
> Ahmad
> 
> 
> >
> >
> 
> 
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