Re: Proposal to revise the new parsing of PCI selectors (was: Re: HEADS UP: [cvs commit: src UPDATING src/share/man/man4 pci.4 src/share/man/man9 pci.9 src/sys/amd64/include legacyvar.h src/sys/amd64/amd64 legacy.c src/sys/amd64/pci pci_bus.c src/sys/arm/xscale/i80321 i80321_pci.c src/sys/arm/xscale/ixp425 ...)

On Monday 01 October 2007 09:25:48 am Marius Strobl wrote:
> On Mon, Oct 01, 2007 at 02:49:12PM +0200, Stefan Esser wrote:
> > Marius Strobl wrote:
> > > On Sun, Sep 30, 2007 at 03:34:57PM -0700, Marcel Moolenaar wrote:
> > >> On Sep 30, 2007, at 3:17 PM, Marius Strobl wrote:
> > >>
> > >>>> Where it would previously succeed, I now get ..
> > >>>>
> > >>>> toshi# pciconf -wb pci0:30:0 0x1a 8
> > >>>> pciconf: ioctl(PCIOCWRITE): Operation not supported by device
> > >>>>
> > >>> As mentioned the format of the location strings has changed,
> > >>> you probably need to use pci0:0:30:0.
> > >> If compatibility is a concern, we may be able to make the parsing
> > >> a bit more smart without too much complexity. We can count the
> > >> number of colons for exampl,e and assume missing elements are 0.
> > >> So, if one enters pci1:2:3, the domain will be 0. If one enters
> > >> pci4:5, both the domain and bus will be 0, etc.
> > >>
> > >> Just a thought...
> > >>
> > > 
> > > Unfortunately, for pciconf(8) the function is already optional
> > > so pci1:2:3 would be ambiguous.
> > 
> > 
> > Well, since it was me who chose to parse it that way, when pciconf
> > saw the light of day, I can say that the logical extension appears
> > to be the support of 3 formats for the PCI device selector:
> > 
> > pci1:2:3:4  (full, domain/bus/slot/function, required if domain!=0)
> > pci2:3:4    (abridged, in case the domain is "0")
> > pci2:3      (abridged, in case the domain and function are "0")
> > 
> > 
> > Since most devices are on a system with just a single PCI host
> > adapter, the two abridged formats could still be used, as before.
> > 
> > Just in case of multiple PCI domains, the full 4 value form was
> > required for any domain other than "0".
> > 
> > No compatibility problems, and the 3 value form would keep the
> > current meaning (it would become domain/bus/slot now).
> > 
> > This appears to be in compliance with POLA. It means, that all the
> > current scripts (which may be shared between 6.x and 7.x) can stay
> > unmodified, since the 2- and 3-value formats keep their semantics.
> > And if PCI domains are used, its obvious there are no compatibility
> > issues (since they are no present in 6.x).
> > 
> > 
> > Since this was a change to my original code, I'd like to make the
> > change I outlined above, unless there are strong objections.
> > 
> 
> I'm ok with what you propose, I'd wait for John to comment
> whether he sees any issues regarding the hints feature he is
> working on though.

This sounds good to me.

-- 
John Baldwin