From: Bjorn Helgaas <bhelgaas@google.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: sumit chaudhary <flyingbee.linux@gmail.com>, linux-pci@vger.kernel.org
Subject: Re: 64 bit address to a pcie card
Date: Thu, 5 Jul 2012 21:49:23 -0600 [thread overview]
Message-ID: <CAErSpo4mw9+rvRw2jqX54Yw27FdXV89faA7KEcPwz2Y284s9WQ@mail.gmail.com> (raw)
In-Reply-To: <CAE9FiQWCeBRfwA2D+GoLCv+97KbzA5c-Fv76NZz7BOyLE7HoWQ@mail.gmail.com>
On Thu, Jul 5, 2012 at 6:14 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Thu, Jul 5, 2012 at 8:16 AM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>> [Added back cc: linux-pci so others can help, too]
>>
>> What exactly is the problem? Is there a device that isn't working as expected?
>>
>> The device at 07:00.0 does indeed have 64-bit BARs, and they happen to
>> be assigned addresses below 4GB:
>>
>> pci 0000:07:00.0: reg 10: [mem 0xfddff000-0xfddfffff 64bit]
>> pci 0000:07:00.0: reg 18: [mem 0xbf000000-0xbfffffff 64bit pref]
>> pci 0000:07:00.0: reg 20: [mem 0x40000000-0x7fffffff 64bit pref]
>>
>> This is perfectly normal. The fact that the BAR supports a full
>> 64-bit address doesn't mean it has to be assigned space above 4GB.
>> The BIOS assigned these addresses, and Linux found no reason to change
>> them, so we just left them alone.
>
> The system only has 1G ram installed, and the card need 1G 64bit pref.
>
> Maybe BIOS could push that above 4G, if the system get 4G RAM installed.
Maybe. I doubt it, because BIOS didn't report any host bridge
apertures above 4GB.
But I haven't heard about a problem yet. If there's no problem,
there's no problem.
next prev parent reply other threads:[~2012-07-06 3:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-04 6:33 64 bit address to a pcie card sumit chaudhary
2012-07-04 13:59 ` Bjorn Helgaas
[not found] ` <CAJkVMNpZaMKm8tc+axdOBySpp68_j=EegEUOO+B=cYudsxNCgw@mail.gmail.com>
2012-07-05 15:16 ` Bjorn Helgaas
2012-07-06 0:14 ` Yinghai Lu
2012-07-06 3:49 ` Bjorn Helgaas [this message]
2012-07-09 5:39 ` sumit chaudhary
2012-07-09 8:41 ` Yinghai Lu
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