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    SubjectRe: [PATCH v2 2/5] x86/PCI: Support additional MMIO range capabilities


    On 04/30/2014 02:00 AM, Robert Richter wrote:
    > On 29.04.14 15:40:28, Myron Stowe wrote:
    >> On Tue, Apr 29, 2014 at 1:14 PM, Borislav Petkov <bp@alien8.de> wrote:
    >>> So sounds to me like we want to get rid of the whole IO ECS deal
    >>> altogether then.
    >>>
    >>> Now, I'm wondering whether we should kill it completely since I don't
    >>> think anyone cares about numa node info being correct on K8, or? I'm
    >>> specifically turning to our numascale friends who love to have a lot of
    >>> nodes. :-)
    >
    > Maybe I did get you wrong, but IO ECS was introduced with fam10h and
    > is not related to k8.
    >
    >> I think we need to be careful here as there are two unrelated topics
    >> being discussed together. What started this whole thread was the need
    >> for sysfs related numa_node information with respect to PCI devices
    >> (1). Without patch 1, platforms with newer AMD CPUs end up having
    >> '-1' numa_node values for all PCI devices.
    >>
    >> IO ECS has no bearing on patch 1, it only comes into play with patch 2
    >> which is concerned with MMIO resource information when MCFG doesn't
    >> exist. For the particular issue I'm trying to get resolved, patch 2
    >> is not needed. However, since we have expended time and effort on
    >> this subject, perhaps we should get this cleaned up while it has our
    >> attention.
    >>
    >> I'm all for deleting as much of amd_bus.c as possible due to its
    >> "perennial maintenance headache". The obvious choices seem to be all,
    >> or some combination, of:
    >> o removing IO ECS logic,
    >> o removing IO/MMIO logic (assuming MCFG issues were long enough ago
    >> to no longer be a concern),
    >> o start deprecating amd_bus.c by adding logic to skip if BIOS >= 2015
    >
    > I don't see any reason for big changes actually. Just bind the IO ECS
    > logic to fam10h (either with fam check or pci device depending on the
    > implementation, xen's flavor would be pci). This is something stricter
    > than 'if BIOS >= 2015'. It leaves code as it is which is maintainable.
    >
    > You implement the new logic for for newer families. No need for one
    > implementation that fits all.
    >
    > -Robert
    >
    Actually, if ECS is needed by IBS, then wouldn't this still be needed
    for every family since 10h and later (except family11h).

    Suravee


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