[PATCH] PCI bus number management

[David Shane Holden]

On 02/06/14 14:37, John Baldwin wrote:
> I have a patch to teach the PCI bus code and PCI-PCI bridge driver to
> manage PCI bus numbers.  The approach is somewhat similar to how
> NEW_PCIB manages I/O windows for briges.  Each bridge creates an rman
> to manage the bus numbers for all buses and bridges that live below
> it.  Each bus allocates a bus resource from its parent bridge, and
> child bridges allocate their ranges from their parent devices. At the
> "top" of the PCI tree, the Host-PCI bridges allocate their respective
> bus ranges from their PCI domain/segment.  There isn't really a
> device node for PCI domains, so I created a helper API that basically
> auto- creates a PCI bus rman for each domain on first use and then
> sub-allocates from that for Host-PCI bridges.
>
> The current patch (with some extra debugging) is at
> http://people.FreeBSD.org/~jhb/patches/pci_bus_rman.3.patch
>
> I would like to commit this to HEAD soon but thought I would post it
>  for some pre-commit testing for the brave. :)  If you are really
> brave, try booting with 'hw.pci.clear_buses=1' which will force the
> kernel to renumber all buses in the system.  If you are really,
> really brave, try booting with 'hw.pci.clear_bars=1',
> 'hw.pci.clear_buses=1', and 'hw.pci.clear_pcib=1'.  (My laptop
> survives with all those set)
>
> Note that the patch only enables bus number management on amd64 and
> i386.  I believe ia64 just needs to define PCI_RES_BUS for this to
> work since it mandates ACPI.  Porting this to other platforms
> requires handling PCI_RES_BUS rseources for Host-PCI bridges in
> bus_alloc_resource(), bus_adjust_resource(), and
> bus_release_resource().
>

Setting all 3 on an Atom D510MO works fine.  On a Lenovo W520 though
hw.pci.clear_bars=1 causes a lockup during boot.  The last few lines
with a normal boot are:

pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pcib0: decoding 5 range 0-0xfe
pci0: <ACPI PCI bus> on pcib0
	secbus=1, subbus=1
pci0:0:1:0: allocated initial secbus range

While a verbose boot produces:

pcib0: allocated type 3 (0xc0000400-0xc00007ff) for rid 10 of pci:0:0:26:0
pcib0: matched entry for 0x26.INTA
pcib0: slot 26 INTA hardwired to IRQ 26

And it ends there.  Setting the other 2 are fine though.