Subject: Re: -current bha driver attaches PCI device multiple times (as ISA)
To: Justin T. Gibbs <gibbs@freefall.freebsd.org>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: current-users
Date: 10/08/1996 02:26:31
>I believe there is a way to disable the ISA-compatible I/O port from
>the PCI probe so that there is no penalty in leaving the ISA port
>enabled in the BIOS. Here's a code snippet from the Linux driver:
[snip]
Thank you for pointing that out; but, as it happens, I had that in an
editor buffer at the time I sent the message. I assumed we didn't
need explicit advice to look at other souce.
In fact, the linux driver is where I gleaned the idea of using the
BusLogic id string byte that identifies a parent bus type. That fits
the NetBSD model of separate bus-specific attach front-ends rather
well. My apologies for not attributing that idea.
It does, of course, leave open the issue of whether it's
architecturally preferable for the NetBSD Buslogic attach functions
to
a) autodisable the ISA ports on a PCI buslogic adaptor
(when the ports were not disabled by the user via the
SCSI BIOS) , making the releveant io ports available for
other, conflicting devices; or
b) leave a PCI/EISAthe BusLogic card which is
BIOS-configured to respond to ISA primary or secondary
addresses in that state, whilst _not_ configuring the
alreayd-configured PCI devices as an ISA device too.
(or both).
This could make a difference to, for instance, user-space direct
access to the relevant io ports. I concede that's a far-fechted
example. It's not clear (to me) whether it's better for the kerrnel
to second-guess the user by disabling access to a PCI card via the
standard ISA ioports.
It *is* clear that not booting, with a default/distribution config, in
the hardwre configuration *mandated* by NetBSD 1.2, is a palpable bug.
I took all the above as read, on the principle that Charles Hannum
(who seems to have touched the NetBSD buslogic drivers most) would
also take it as read. As best I understand, that's the communication
protocol he prefers. My apologies to anyone who needed to have that
pointed out explicitly. It's always hard to please a wide-ranging audience.