Re: DRAM and PCI devices at same physical address

From: Matt Porter (mporter_at_kernel.crashing.org)
Date: 06/27/04

  • Next message: Matthew Dharm: "Re: drivers/block/ub.c" 
    Date:	Sat, 26 Jun 2004 20:26:48 -0700
To: Matt Sexton <sexton@mc.com>

    On Fri, Jun 25, 2004 at 05:23:00PM -0400, Matt Sexton wrote:
    > I have a dual Xeon system with the Lindenhurst (E7710) chip set and 1 GB
    > of memory. In order to reserve a very large block of memory for a
    > (user-space) device driver I am writing, I pass "mem=XX" to the kernel
    > at boot time. Unfortunately, /proc/pci shows two devices now appearing
    > in the reserved upper memory range.

    <snip>
     
    > The devices always appear right after the limit I specify on the kernel
    > boot line. If I specify "mem=512M", then the first device appears at
    > 0x20000000. If I specify nothing, then it appears at 0x40000000. All
    > other PCI devices show up at addresses of 0xDD000000 and above.
    >
    > Is there any way to prevent these devices from showing up in the
    > physical address range of my reserved memory?

    You could try using reserve_bootmem() to reserve your driver memory.

    > Should they be appearing there at all? Does Linux make any guarantees
    > when there is more physical memory than specified by "mem=" ?

    Depends on the arch, I don't know what ia32 does.
     
    -Matt
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  • Next message: Matthew Dharm: "Re: drivers/block/ub.c"

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