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Re: [qemu-s390x] [Qemu-devel] [PATCH v2 1/6] s390x/pci: Fix primary bus

From: Collin Walling
Subject: Re: [qemu-s390x] [Qemu-devel] [PATCH v2 1/6] s390x/pci: Fix primary bus number for PCI bridges
Date: Mon, 4 Feb 2019 17:58:18 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1

On 1/30/19 10:57 AM, David Hildenbrand wrote:
The primary bus number corresponds always to the bus number of the
bus the bridge is attached to.

Right now, if we have two bridges attached to the same bus (e.g. root
bus) this is however not the case. The first bridge will have primary
bus 0, the second bridge primary bus 1, which is wrong. Fix the assignment.

While at it, drop setting the PCI_SUBORDINATE_BUS temporarily to 0xff.
Setting it temporarily to that value (as discussed e.g. in [1]), is
only relevant for a running system that probes the buses. The value is
effectively unused for us just doing a DFS.

Also add a comment why we have to reassign during every reset (which I
found to be surprising.

Please note that hotplugging of bridges is in general still broken, will
be fixed next.

[1] http://www.science.unitn.it/~fiorella/guidelinux/tlk/node76.html

Reviewed-by: Thomas Huth <address@hidden>
Signed-off-by: David Hildenbrand <address@hidden>

Reviewed-by: Collin Walling <address@hidden>

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