Re: CVS commit: src/sys/dev/isa

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

dyoung%pobox.com@localhost said:
> How many pcdisplay at isa can there be one machine?

Iirc, this code is originating from alpha where you can have
multiple independant PCI/ISA/EISA hierarchies and thus
multiple pcdisplay/ega/vga devices.

> Can the two tags that pcdisplay_is_console() compared ever come from
> different spaces?

Yes, if there are independant ISA buses they are distinguished
by their tags.

> pcdisplay_is_console does not compare tag-handle tuples, it compares
> only tags.  Can it tell two instances of pcdisplay apart in that way?

I think this is just a simplification -- since you can have only one
pcdisplay per bus hierarchy you can have only one per tag.

> > MI code needs to be able to check for equality at least.
> I don't see the need.

This is done at other places as well, eg in com.c, which is used
by many (also embedded) architectures. (In this case, tag _and_
handle are compared -- one can have multiple com devices in any
of multiple address spaces.)

best regards
Matthias



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