From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kristen Accardi <kristen.c.accardi@intel.com>
Subject: Re: [patch 2/2] i386/x86_64: collect host bridge resources v2
Date: Tue, 28 Jun 2005 11:21:54 -0700
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Sender: linux-kernel-owner@vger.kernel.org
To: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: rajesh.shah@intel.com, gregkh@suse.de, ak@suse.de, len.brown@intel.com, akpm@osdl.org, linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, acpi-devel@lists.sourceforge.net
List-Id: linux-acpi@vger.kernel.org

On Tue, 2005-06-28 at 15:51 +0400, Ivan Kokshaysky wrote:
> [This refers to "gregkh-pci-pci-collect-host-bridge-resources-02.patch"
> which went into 2.6.12-mm1 and -mm2]
> 
> On Thu, Jun 02, 2005 at 03:41:49PM -0700, rajesh.shah@intel.com wrote:
> > This patch reads and stores host bridge resources reported by
> > ACPI BIOS for i386 and x86_64 systems.  This is needed since
> > ACPI hotplug code now uses the PCI core for resource management. 
> 
> That patch introduces two major problems.
> 
> 1. The new root bus resources aren't properly inserted into global
>    resource tree (missing request_resource calls). This leads to
>    completely messed up PCI setup, especially with
>    pci_assign_unassigned_resources() call, as seen in -mm1 (mm2 is
>    also unsafe, though).
> 
> 2. Transparent bridge handling is broken, no matter is it old code
>    in Linus' tree or the new one in -mm. At the point then
>    pcibios_setup_root_windows() is called, the "transparent"
>    resource pointers have been already set up in pci_read_bridge_bases()
>    (typically to ioport_resource and iomem_resource), so after changing
>    the root bus windows these pointers are wrong.
> 
> The appended patch fixes that. Just compare /proc/ioports and /proc/iomem
> with and without it. ;-)
> 


I gave this patch a try (against mm2), and found that I now get many
errors on boot up complaining about not being able to allocate PCI
resources due to resource collisions, and then the system begins to
complain about lost interrupts on hda, and is never able to mount the
root filesystem.
Kristen


> Ivan.
> 
> --- 2.6.12-mm2/arch/i386/pci/acpi.c	2005-06-28 13:30:24.000000000 +0400
> +++ linux/arch/i386/pci/acpi.c	2005-06-28 14:13:51.000000000 +0400
> @@ -107,10 +107,22 @@ verify_root_windows(struct pci_bus *bus)
>  			continue;
>  		switch (bus->resource[i]->flags & type_mask) {
>  			case IORESOURCE_IO:
> -				num_io++;
> +				if (!request_resource(&ioport_resource,
> +						      bus->resource[i]))
> +					num_io++;
> +				else {
> +					kfree(bus->resource[i]);
> +					bus->resource[i] = NULL;
> +				}
>  				break;
>  			case IORESOURCE_MEM:
> -				num_mem++;
> +				if (!request_resource(&iomem_resource,
> +						      bus->resource[i]))
> +					num_mem++;
> +				else {
> +					kfree(bus->resource[i]);
> +					bus->resource[i] = NULL;
> +				}
>  				break;
>  			default:
>  				break;
> @@ -126,6 +138,21 @@ verify_root_windows(struct pci_bus *bus)
>  }
>  
>  static void __devinit
> +fixup_transparent_bridges(struct list_head *bus_list)
> +{
> +	int i;
> +	struct pci_bus *b;
> +
> +	list_for_each_entry(b, bus_list, node) {
> +		if (b->self && b->self->transparent) {
> +			for (i = 3; i < PCI_BUS_NUM_RESOURCES; i++)
> +				b->resource[i] = b->parent->resource[i - 3];
> +		}
> +		fixup_transparent_bridges(&b->children);
> +	}
> +}
> +
> +static void __devinit
>  pcibios_setup_root_windows(struct pci_bus *bus, acpi_handle handle)
>  {
>  	int i;
> @@ -147,6 +174,21 @@ pcibios_setup_root_windows(struct pci_bu
>  			kfree(bus->resource[i]);
>  			bus->resource[i] = bres[i];
>  		}
> +	} else {
> +		/* Squeeze out unused resource pointers. */
> +		int idx = 0;
> +
> +		for (i = 0; i < PCI_BUS_NUM_RESOURCES; i++) {
> +			if (bus->resource[i])
> +				bus->resource[idx++] = bus->resource[i];
> +		}
> +		for (; idx < PCI_BUS_NUM_RESOURCES; idx++)
> +			bus->resource[idx] = NULL;
> +
> +		/* The root bus resources have been changed. Fix up the
> +		   resource pointers of buses behind "transparent" bridges
> +		   as well. */
> +		fixup_transparent_bridges(&bus->children);
>  	}
>  }
>