EV-64260-BP & GT64260 bi_recs

Geert Uytterhoeven geert at linux-m68k.org
Mon Mar 25 19:51:20 EST 2002

On Sun, 24 Mar 2002, Benjamin Herrenschmidt wrote:
> Which means that as soon as you want to add more infos, you will have
> to deal with all the pre-bi_rec problems when you own stuffs have to
> evolve. (versionning etc...).
> Again, for anything not realted to device drivers infos (things like
> HW ethernet addresses, PHY IDs, eventually interrupt routing), a whole
> bunch of bi_rec types will be left free by the kernel for use by your
> proprietary stuff the way you want, so you can pretty much define
> whatever you want (or not, it's up to you).
> But, I feel it's more convenient for drivers to use this signle-level
> BI_DEVICE bi_rec that contains itself bi_recs.
> >I really agree with Dan Malek on this - we shouldn't use bi_recs as a
> >way to reimplement methods of passing information that already exist,
> >for example, the __setup() functions.  It should be a way of passing
> >information that only a bootloader can know, such as the location of a
> >ramdisk, or the command line that the user typed into the bootloader.
> Which is exactly what I'm proposing. Passing generic informations like
> CPU core clocks, command line, ramdisk, etc... is done via bi_recs at
> the toplevel.
> The BI_DEVICE bi_rec's allow to provide other informations that are
> also only known by the firmware (most of the time), like eth MAC
> address, PHY wiring, or other kind of wiring informations related
> to a given rev. of a board, etc... provided that those infos
> concern a given driver for a specific device. It's also a convenient
> way to provide interrupt routing informations.

Alternatively, why not create a whole device tree for this? There already
exists a standard for device trees: IEEE 1275 Open Firmware. Then you need only
one extra bi_rec tag: BI_OF_TREE.



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

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