Re: [Qemu-devel] nonzero LUN on USB Bulk Only Transfer fails with QEMU+edk2

[Laszlo Ersek]

On 02/19/19 09:49, Gerd Hoffmann wrote:
>   Hi,
> 
>> (2) If I change the cmdline to "lun=5", then the exchange is:
> 
> Not supported (by the usb protocol).
> 
> The protocol has a control message to query the number of devices (grep
> for GetMaxLun in qemu).  LUNs are not allowed to be sparse.  So, with a
> single storage device the LUN must be zero.  With two devices the LUNs
> must be 0,1, with three 0,1,2 etc., you get the idea :)

Yes, Phil explained the same -- I originally missed this part of the
documentation (because the requirement is documented, so the fault is
clearly mine).

However, once I fixed the configuration (so that I'd have LUNs 0 and 1),
edk2 still tripped an assert. Please see my message elsewhere in this
thread; the fixed config case is marked as item (4).

Thanks!
Laszlo

> Maybe usb-bot should check for that and throw an error, I think right
> now we only have the generic scsi code check which will verify the lun
> isn't too big (<= 15) but will not check the non-sparse requirement.
> 
> cheers,
>   Gerd
>