On 14.12.2016 10:36, Gerd Hoffmann wrote:
> Hi,
>
>>>> in the /chosen/qemu,boot-list property. SLOF, however, probes the
>>>> USB device, recognizes that it is a storage device and thus changes
>>>> its name to "storage", and additionally adds a child node for the
>>>> SCSI LUN, so the correct boot path in SLOF is something like
>>>> "/pci@800000020000000/usb@0/storage@1/disk@101000000000000" instead.
>
> Sure this is correct?
Yes, this is what SLOF is using / expecting.
> usb-storage (aka virtual usb stick) creates paths like this:
>
> /pci@i0cf8/usb@1,2/storage@1/channel@0/disk@0,0
>
> i.e. there is a extra channel element (probably for host adapters with
> multiple scsi busses).
That's true for the default case, but for the pseries machine, there is
already code that changes the boot path for virtual usb-storage devices,
see the function spapr_get_fw_dev_path() :
... else if (usb) {
/*
* We use SRP luns of the form 01000000 | (usb-port << 16) | lun
* in the top 32 bits of the 64-bit LUN
*/
unsigned usb_port = atoi(usb->port->path);
unsigned id = 0x1000000 | (usb_port << 16) | d->lun;
return g_strdup_printf("%s@%"PRIX64, qdev_fw_name(dev),
(uint64_t)id << 32);
}
>>>> So when we detect an USB mass storage device with SCSI interface,
>>>> we've got to adjust the firmware boot-device path properly, so that
>>>> SLOF can automatically boot from the device.
>
>>> Any reason why this is hidden in ppc/spapr?
>>>
>>> usb-host could implement the ->fw_name callback instead to create a name
>>> depending on the device type ...
>
>> The naming is specific to SLOF ... not sure what happens with other
>> firmware implementations, so spapr.c sounds like the better place to me
>> right now.
>
> If usb-host (and usb-redir too btw) create paths identical to the ones
> created by usb-storage. Existing firmware should cope just fine
> (assuming bootindex for usb-storage works).
Which firmware can deal with these original device paths with "channel@0"
in it? Certainly not SLOF. Maybe OpenBIOS? Does OpenBIOS support USB storage
devices?
Thomas
