Re: [PATCH] ata: libata-scsi: Set the RMB bit only for removable media devices

[Niklas Cassel <cassel@kernel.org>]

On Thu, Jun 13, 2024 at 07:33:53PM +0200, Niklas Cassel wrote:
> 
> This is however wrong. See "20-082r23SPC-6: Removable Medium Bit
> Expectations" which has since been integrated to SPC, which states that:
> 
> """
> Reports have been received that some USB Memory Stick device servers set
> the removable medium (RMB) bit to one. The rub comes when the medium is
> actually removed, because... The device server is removed concurrently
> with the medium removal. If there is no device server, then there is no
> device server that is waiting to have removable medium inserted.
> 
> Sufficient numbers of SCSI analysts see such a device:
> - not as a device that supports removable medium;
> but
> - as a removable, hot pluggable device.
> """
> 
> The definition of the RMB bit in the SPC specification has since been
> clarified to match this.
> 
> Thus, a USB stick should not have the RMB bit set (and neither shall an
> eSATA nor a hot-plug capable port).

Since SPC-6 does make it quite clear that USB Memory Stick device servers
should not have the RMB bit set, Thomas, may I ask what udisks is using to
automount USB sticks?

Since USB sticks that follow SPC-6 clearly cannot have RMB bit set,
which means that SCSI core will set removable:
(the equivalent of:)
/sys/devices/pci0000:00/0000:00:04.0/ata3/host2/target2:0:0/2:0:0:0/block/sda/removable
to 0.


Kind regards,
Niklas