Subject: Re: Before and after the 1.1 release: pcmcia
To: None <port-i386@NetBSD.ORG>
From: None <rvb@IGW.TRUST.CS.CMU.EDU>
List: port-i386
Date: 10/11/1995 02:44:56
------- Start of forwarded message -------
A few comments about the pcmcia interface discussions:
1. I also agree that it is pretty important to get a
pcmcia interface into the kernel. One has been floating
around for 9 plus months. This is too long. It makes
it hard on people who want to do further development on
laptops, support new pcmcia devices ...
2. "The pcic-chip can have only 2 devices.
And unless I goofed somewhere the limit is on the chip-driver and not
in the pcmciabus framework."
This statement is incorrect. The Intel 82365 architecture
was setup to support 8 slots. I believe that you are
correct, that an individual chip only supports 2 slots.
There is also some magic on how you address the device
registers for a slot. The first 4 slots are accessed thru
ports 0x3e0 & 0x3e1. The second 4 slots are accessed thru
ports 0x3e2 and 0x3e3. (For the curious each slots has 0x40
devices registers; 4*0x40 = 256) The bottom line is that
an IBM 701C (or 755) has two pcmcia slots (the first two
addressed at 0x3e0 & 0x3e1). The IBM Dock II also has two
pcmcia slots (these are addressed as the first two slots at
0x3e0 & 0x3e1). So I would say that slots 0, and 1 and 4
and 5 are available.
3. ... The main reason for it's absence is, that you need to modify all drivers
used with PCMCIA, to not crash or hang the system if the card is removed.
This is going to be pretty near impossible. You have to
guard every port reference that is used anywhere in the
driver to accept the possibility that the card was pulled
out and the value is bogus. You then have to get out of
whatever nesting of routines the code is in.
4. Last point. If a user level program is necessary to
turn on pcmcia ethernet cards, (I got this impression from
previous comments.) please don't forget to put this program
on the install floppy.