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Date: Fri, 25 May 2012 14:58:52 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Bjorn Helgaas <bhelgaas@google.com>
CC: Yinghai Lu <yinghai@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Newbury <steve@snewbury.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 02/11] PCI: Try to allocate mem64 above 4G at first
References: <1337754877-19759-1-git-send-email-yinghai@kernel.org> <1337754877-19759-3-git-send-email-yinghai@kernel.org> <CA+55aFzd1BWqidt95qZLc1x_YU=WeGS=mKUOMvO_3omOhc_5VA@mail.gmail.com> <CAE9FiQXx_x9M5ncLk4DyL8heYQTcsHZt2JofFMjPfUd4mympeA@mail.gmail.com> <CAE9FiQX=ECg5BmKm7B2ua_rZ6bOsceeHNsfFQRWBbNZx+8sBfw@mail.gmail.com> <20120525043651.GA1391@google.com> <CAE9FiQXvYH4zCqp_uOb2nw7jvm8B=q3yx1tCjJUT+PkdymYEuw@mail.gmail.com> <CAE9FiQW0rm2_sKdSCWs3TfatJB9yHwvmvt9_vBYMtOq_YBbmfw@mail.gmail.com> <20120525193716.GA8817@google.com> <CAE9FiQWrZaBpT1fzC_-mSBfDd4AKGrdGomPxVNSU-SFPrVNvOw@mail.gmail.com> <CAErSpo7d+zn-qgWKcbro7yneXRtmZQCOHi+kiGzYUTfs+aiF4g@mail.gmail.com>
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On 05/25/2012 02:55 PM, Bjorn Helgaas wrote:
> 
> I think we actually have a separate bug here.  On 64-bit non-x86
> architectures, PCIBIOS_MAX_MEM_32 is a 64-bit -1, so the following
> attempt to avoid putting a 32-bit BAR above 4G only works on x86,
> where PCIBIOS_MAX_MEM_32 is 0xffffffff.
> 
>         /* don't allocate too high if the pref mem doesn't support 64bit*/
>         if (!(res->flags & IORESOURCE_MEM_64))
>                 max = PCIBIOS_MAX_MEM_32;
> 
> I think we should fix this with a separate patch that removes
> PCIBIOS_MAX_MEM_32 altogether, replacing this use with an explicit
> 0xffffffff (or some other "max 32-bit value" symbol).  I don't think
> there's anything arch-specific about this.
> 
> So I'd like to see two patches here:
>   1) Avoid allocating 64-bit regions for 32-bit BARs
>   2) Try to allocate regions above 4GB for 64-bit BARs
> 

Do we also need to track the maximum address available to the CPU?

	-hpa