Re: [patch 6/7] s390: ipl device.

[Heiko Carstens <heiko.carstens@de.ibm.com>]

> > Export the ipl device settings to userspace via the sysfs:
> >  * /sys/kernel/ipl_device
> What?  Why that location?  Why not in the proper location for your
> device, on your bus?

This interface tells from where the kernel was booted from. I don't
think a device should have an attribute where the meaning would be
"the current running kernel came via this device into memory".
IMHO this should be an attribute of the kernel and therefore I
thought /sys/kernel would be a good idea.

> >    Contains a string in on of the following formats:
> >    1) "ccw <bus_id>", or 2) "fcp <bus_id>,<wwpn>,<lun>".
> >  * /sys/kernel/ipl_parameter
> >    is a binary interface that exports the ipl  parameter block for
> >    scsi ipl. For non-scsi ipl the ipl_paramter is irrelevant.
> Again, put this in your device directory, not in /sys/kernel/

Same here.

> > +static ssize_t
> > +ipl_device_show(struct subsystem *subsys, char *page)
> > +{
> > +	struct ipl_parameter_block *ipl = IPL_PARMBLOCK_START;
> > +
> > +	if (!IPL_DEVNO_VALID)
> > +		goto type_unknown;
> > +	if (!IPL_PARMBLOCK_VALID)
> > +		goto type_ccw;
> > +	if (ipl->hdr.header.version > IPL_MAX_SUPPORTED_VERSION)
> > +		goto type_unknown;
> > +	if (ipl->fcp.pbt != IPL_TYPE_FCP)
> > +		goto type_unknown;
> > +
> > +	return sprintf(page, "fcp 0.0.%04x,0x%016llx,0x%016llx\n",
> > +		       ipl->fcp.devno,
> > +		       (unsigned long long) ipl->fcp.wwpn,
> > +		       (unsigned long long) ipl->fcp.lun);
> > + type_unknown:
> > +	return sprintf(page, "unknown\n");
> > + type_ccw:
> > +	return sprintf(page, "ccw 0.0.%04x\n",ipl_devno);
> 
> That doesn't look like a "single value" from a single file there.  Can't
> you break that up into individual files, based on what exactly is
> present at the time?

Sure, so I would end up with quite a few files:
always a file which tells the type of ipl e.g. ipl_type and dependent
on that additionally:
- in case of ccw ipl:
   just the bus_id of the ipl device (e.g. ipl_bus_id).
- in case of fcp ipl:
   the bus_id, the wwpn and the fcp_lun all exported via different files.

Does that sound reasonable?

Heiko