Re: pci_create_legacy_files() and non root bus

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On Monday, November 10, 2008 10:04 pm Benjamin Herrenschmidt wrote:
> Hi Jesse !
>
> Any reason why we don't create the legacy_io/mem files for child
> busses ?
>
> The fact that they only exist for PHBs makes it tricky for userspace
> programs to find them
>
> Since they only appear in /sys/class/pci_bus/* which has no hierarchy
> information, a user space program like in my case that gets passed a
> sysfs path to a device, would have to walk back up the chain to find out
> the phb in order to then find it in there.

Yeah, in that case it's a bit more of a pain to find.  Originally though we 
figured that the legacy spaces were per-domain or host bridge resources, so it 
didn't make sense to propagate them down to child busses.  If that's not the 
case for your platform it probably makes sense to let them trickle down.

> I don't see why we can't call pci_create_legacy_files() in
> pci_alloc_child_bus() too though. Any reason ?

I'd have to go make sure the code does the right thing for child buses on 
ia64... /me checks.  I think base ia64 will be ok, but whether sn works would 
depend on how the PROM fills in the legacy_mem address (i.e. it should work 
but would need testing).

-- 
Jesse Barnes, Intel Open Source Technology Center

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