Hi Rusty, On Mon, 2007-02-26 at 09:03 +1100, Rusty Russell wrote: > On Sun, 2007-02-25 at 05:58 +0000, Christoph Hellwig wrote: > > On Tue, Feb 20, 2007 at 03:00:56PM +0200, Artem Bityutskiy wrote: > > > > > +module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000); > > > > > +MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: " > > > > > + "mtd=<name|num>[,<vid_hdr_offs>,<data_offs>]. " > > > > > + "Multiple \"mtd\" parameters may be specified.\n" > > > > > + "MTD devices may be specified by their number or > > > > > name. " > > > > > + "Optional \"vid_hdr_offs\" and \"data_offs\" > > > > > parameters " > > > > > + "specify UBI VID header position and data > > > > > starting " > > > > > + "position to be used by UBI.\n" > > > > > + "Example: mtd=content,1984,2048 mtd=4 - attach > > > > > MTD device" > > > > > + "with name content using VID header offset 1984 > > > > > and data " > > > > > + "start 2048, and MTD device number 4 using > > > > > default " > > > > > + "offsets"); > > > >
> The reason drivers can use __module_param_call is that they can > implement their own "types" for module parameters, which will end up > requiring this. > > Using it directly is only really for backwards compatibility (which is > important!), but for new parameters, this multi-part self-parsing is > nasty. Standard (but admittedly suboptimal) way to do this is having > three parameters module_param_array(name, ...), > module_param_array(header_offset, ...), > module_param_array(data_start, ...). we wanted to be able to ommit some of the parameters and let UBI use resonable defaults if needed. Example where we wanted to explicitly overwrite the offset parameters: mtd=content,1984,2048 Example where we did not want it but let instead UBI figure out resonable parameters: mtd=4 With the three arrays we did not see a nice way of achieving this. ubimtds=content,4,7 hdroffs=1984,?,1984 dataoff=s2048,?,2048 The ? look odd, don't they? We also looked at the slram parameters which are like this: slram=name0,addr0,+size0,name1,addr1,+size1 and found that if we wanted to add one more parameter e.g. width it cause likely an interface change: slram=name0,addr0,+size0,width0,name1,addr1,+size1,width1 Finally we found that we liked the phram parameter parsing (which is essentially the same) and did it similar to that. Frank - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/