[SeaBIOS] [PATCH 0/9] add support for generic lun enumeration

[Kevin O'Connor]

On Wed, Mar 01, 2017 at 01:45:33PM +0300, Roman Kagan wrote:
> A number of SCSI drivers currently only see luns #0 in their targets.
> 
> This may be a problem when drives have to be assigned bigger lun
> numbers, e.g. because the storage controllers don't provide enough
> target numbers to accomodate all drives.
> (In particular, I'm about to submit a driver for Hyper-V VMBus SCSI
> controller which is limited to 2 targets only).
> 
> This series adds generic SCSI lun enumeration (either via REPORT LUNS
> command or sequentially trying every lun), and makes the respective
> drivers use it.

Thanks.  Let me make sure I understand this series.  Some scsi
controllers have hardware specific mechanisms for finding the number
of luns (usb-msc, megasas, pvscsi) and some controllers use a generic
REPORT LUNS mechanism (virtio-scsi, esp-scsi, usb-uas, mpt-scsi,
lsi-scsi).

The basic difficulty with implementing REPORT LUNS in seabios is that
the code needs a "struct drive_s" to issue the REPORT LUNS command,
but since the drive parameters (or even the number of drives) aren't
known, a dummy "lun0" drive_s must be created just for REPORT LUNS.
Thus the series breaks the driver xxx_add_lun() functions into
xxx_init_lun() and xxx_add_lun() so that a dummy lun0 can be created.

An additional complexity is that the REPORT LUNS mechanism is broken
in current QEMU on lsi-scsi and mpt-scsi.

Your goal is to add support for "Hyper-V VMBus SCSI" which also
requires REPORT LUNS.

Is the above correct?

-Kevin