Port-i386 archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: no ndis* at cardbus?

dyoung%pobox.com@localhost said:
> > For a minimal gain, it would make even more a mess of the
> > PCI framework, and it would be in the way of proper
> > PCIexpress/Expresscard support.
> I think that you may have made some assumptions that you are not
> telling us about. 

It doesn't need assumptions, just facts.
There are significant differences: autoconfiguration (no device
addressing), interrupts and power management. The latter two
are actually areas which are somehow delicate.
Merging this into the PCI framework would require conditionals
and hooks which noone would understand anymore after a while.
(OK, that's an assumption, but a well based one.)
In any case it is the opposite of modularity.

Also, pci and cardbus are controlled by different standards
bodies (PCISIG vs PICMG). This means that while it is already
hard to meet someone with access to one of the specs, it is
even more unlikely that someone hacking on the code can
check against both.

The vendor/device IDs are kept coherent, but a chip designed
for PCI will not work on cardbus unless specifically designed
for this. So the cardbus namespace is much much smaller, and
it will stay that way.
A cardbus does only show up behind a "cbb", and we need a specific
driver for cbbs anyway for power handling etc. This is quite
different from the situation in PCI where we can handle unknown
bridges because they are standardized.

>From my perspective, deleting a zillion redundant device attachments

There are nineteen atm, and while we might still grow some hardware
support it will be a handful more if at all.
Cardbus is dead, most new laptops don't have it.
It's also not so rendundant because it contains the cardbus
specific power handling. (I agree that some more code could
be shared but I suspect that spec availability is a bit
in the way here.)

And the cardbus code uses "rbus" which is somewhat fragile. Without
a good reason I'd prefer to keep it away from the PCI code.

> Integration of CardBus and PCI could be the
> foundation for proper PCIe / ExpressCard support

A "foundation" (buzzword bingo or what) would be the lowest
common denominator for me, not something where special cases
are merged in.

best regards

Forschungszentrum Juelich GmbH
52425 Juelich

Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzende des Aufsichtsrats: MinDir'in Baerbel Brumme-Bothe
Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender),
Dr. Ulrich Krafft (stellv. Vorsitzender), Prof. Dr. Harald Bolt,
Dr. Sebastian M. Schmidt

Home | Main Index | Thread Index | Old Index