On Tue, Jul 3, 2012 at 1:33 AM, Taku Izumi <izumi.taku@xxxxxxxxxxxxxx> wrote:
>
> Hi Yinghai,
> Thank you for your comment.
>
> On Mon, 2 Jul 2012 13:51:59 -0700
> Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>
>> On Sun, Jul 1, 2012 at 9:49 PM, Taku Izumi <izumi.taku@xxxxxxxxxxxxxx> wrote:
>> >
>> > Currently I/O ports and I/O memory resources are reserved for
>> > hotplug bridges and we can tune their size by using hpiosize
>> > and hpmemsize boot option.
>> >
>> > This patch extends feature so that we can reserve additional
>> > bus number resources for hotplug bridges and tune it by
>> > using "hpbussize" option.
>> >
>> > This patch also adds missing document for "hpiosize" and
>> > "hpmemsize" option.
>> >
>> > Signed-off-by: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
>> > ---
>> > Documentation/kernel-parameters.txt | 10 ++++++++++
>> > drivers/pci/pci.c | 6 +++++-
>> > drivers/pci/probe.c | 4 ++++
>> > include/linux/pci.h | 1 +
>> > 4 files changed, 20 insertions(+), 1 deletion(-)
>> >
>> > Index: linux/drivers/pci/pci.c
>> > ===================================================================
>> > --- linux.orig/drivers/pci/pci.c
>> > +++ linux/drivers/pci/pci.c
>> > Index: linux/drivers/pci/probe.c
>> > ===================================================================
>> > --- linux.orig/drivers/pci/probe.c
>> > +++ linux/drivers/pci/probe.c
>> > @@ -865,6 +865,10 @@ int __devinit pci_scan_bridge(struct pci
>> > /*
>> > * Set the subordinate bus number to its real value.
>> > */
>> > + if (dev->is_hotplug_bridge) {
>> > + if (max + pci_hotplug_bus_size < child->busn_res.end)
>> > + max += pci_hotplug_bus_size;
>> > + }
>> > pci_bus_update_busn_res_end(child, max);
>> > pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
...
> I don't think this feature conflicts with your feature.
> Even if we can reallocate bus number automatically, I'd like to
> avoid that situation preferably, so I'd like to keep bus number
> resource for hotplug bridge in advance.
>
> Can't you agree with me?
>
that add may not be safe, before busn_alloc patchset, that
busn_res.end should be 0xff.
so you add extra bus range that could overlap other bridge.
after busn_alloc patchset:
/*
* Set the subordinate bus number to its real value.
*/
if (dev->is_hotplug_bridge && child->busn_res.end > max &&
(max - child->busn_res.start) < HOTPLUG_BRIDGE_RESERVE_BUSNR)
max = min_t(int, child->busn_res.start +
HOTPLUG_BRIDGE_RESERVE_BUSNR,
child->busn_res.end);
shrink_size = (int)child->busn_res.end - max;
pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
pci_bus_update_busn_res_end(child, max);
and it will try to shrink less to preserve more space for later usage.
now
#define HOTPLUG_BRIDGE_RESERVE_BUSNR 8
so I assume that you want that value to be changeable via command line?
Thanks
Yinghai
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