linux-kernel - Re: [PATCH 3/4] PCI: restrict subordinate buses to those reachable via host bridge

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Message-ID: <CAE9FiQXj8W4G_SRKCFU-gHJRZ+qENPAs8WAcZA_PVgoageHcoQ@mail.gmail.com>
Date:	Thu, 19 Jan 2012 12:42:20 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ram Pai <linuxram@...ibm.com>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>, linux-pci@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] PCI: restrict subordinate buses to those reachable
 via host bridge

On Wed, Jan 18, 2012 at 9:46 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> On Wed, Jan 18, 2012 at 10:27 AM, Yinghai Lu <yinghai@...nel.org> wrote:
>> On Wed, Jan 18, 2012 at 8:52 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
>>> If we make a quirk for this machine, we still have the question of
>>> what to do with my patches.  I assert that if Linux ever reconfigures
>>> any bus numbers or does any configuration of hot-added P2P bridges, it
>>> must pay attention to the host bridge bus number window.  Therefore, I
>>> think we need something like this series even if we make a quirk.
>>
>> We may need more smart way to find unused bus range instead of just
>> just max+1 and ++max.
>>
>> For example:  one bridge (A) have two child bridges (B and C),
>> A: bus range: 10-2f
>> B: bus range: 11-1f
>> C: bus range: 20-2f
>>
>> when some broken case happen, B bus BIOS assigned bus range will be
>> all cleared in first pass.
>> but C bus is ok.  but in second bus, bus will be assigned to 30- .
>> that is totally wrong, We should still
>> try to use bus 11-1f at first for bus B.
>
> Yes, I agree we may need a better way to choose bus numbers in the
> first place.  My current patch (3/4) doesn't change how we choose
> them; it only rejects invalid ones.

come out draft about bus number tracking and allocate bus range instead.

please check attached patch.

Thanks

Yinghai

View attachment "busn_res_track_alloc.patch" of type "text/x-patch" (11792 bytes)