Date: Fri, 12 Sep 1997 16:14:12 +1000 From: Mike Smith <mike@smith.net.au> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: mike@smith.net.au (Mike Smith), gurney_j@resnet.uoregon.edu, perhaps@yes.no, freebsd-hackers@FreeBSD.ORG Subject: Re: PnP support Message-ID: <199709120614.QAA01493@word.smith.net.au> In-Reply-To: Your message of "Fri, 12 Sep 1997 06:30:16 %2B0200." <199709120430.GAA02186@labinfo.iet.unipi.it>
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> > > > PnP probe > > > > get ISA config (compiled in, datafile, etc.) > > > > > > this means probe the isa devices and trust what the config info > > > say. At this point we have already effectively allocated 'extents' > > > for legacy ISA devices. > > > > No, this means read the compiled in hints for brute-force ISA probes. > > not sure. take the case of GENERIC, where all sort of hardware is > compiled in, possibly at conflicting addresses, and no actual conflicts > are present since not all devices are really present. How do you tell > without probing ? OK, I'm not getting across. You *don't*care* in the gather phase. All you are doing is making a list of where things might be. At some point in the boot phase, you will have all of the information, but have done nothing more intrusive than talk to the PCI BIOS and run a PnP scan. Why do this? Because before we plan anything, we want to know as much as possible. This is also the ideal point for user intervention, where the user can be presented with as much information as possible, but before you have closed any doors to them. Your question about "stuff compiled in" in GENERIC is a non-issue in that the config simply specifies a list of drivers to form part of the initial kernel load, and a set of hints to those drivers in the ISA case. An ISA driver probe routine is then called by the ISA bus code once for each hint, and if the probe passes is then attached. By the stage this is invoked, you have already given up resources > > In the gather phase, we do *nothing* with the hardware that might cause > > any sort of confusion. > > .... > > > > Also, while we are on the subject: some legacy ISA device also have > > > software-configurable resources such as DMA or IRQ channels. methods > > > are device-specific (pre-PnP). > > > > In the case of the 3c509, for example, you have a "pseudo-PnP" probe > > for it which would run just after the "real" PnP probe. As long as the > > "smart" probe can provide the basic information required to configure > > the hardware and select a driver, it qualifies as PnP. > > ok, fine. > > Luigi >
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