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Re: [Xen-devel] PAE guest address maps?

  • To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Randy Thelen <rthelen@xxxxxxxxxx>
  • Date: Wed, 25 Oct 2006 17:14:59 -0700
  • Delivery-date: Wed, 25 Oct 2006 17:15:18 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Randy Thelen wrote:

Folks --

I'm looking through a PAE guest's address map and I'm trying to make sense out of it. Is there some documentation about these address regions:

I meant to annotate the following table a bit more:

0xc0000000 - 0xc0800000: 8MB    <-- My kernel
0xfde00000 - 0xfde04000: 16KB   <-- pfn to mfn ptes
0xfdfac000 - 0xfdfae000: 8KB    NOT READABLE
0xfdfb4000 - 0xfdfc0000: 48KB   NOT READABLE
0xfdfe4000 - 0xfdfe6000: 8KB    NOT READABLE
0xfdfec000 - 0xfdff0000: 16KB   <-- ???
0xfdff4000 - 0xfe000000: 48KB   NOT READABLE

For example, the second entry (that which I think is the pfn to mfn ptes):

(gdb) x/32x xen_phys_machine
0xc028c000:     0x000d16ee      0x000d160e
0xc028c008:     0x000d161b      0x000d161e
0xc028c010:     0x000d1620      0x000fb1fa
0xc028c018:     0x000d1603      0x000d1604
(gdb) x/32g 0xfde00000
0xfde00000:     0x00000000d16ee023      0x00000000d160e023
0xfde00010:     0x00000000d161b023      0x00000000d161e023
0xfde00020:     0x00000000d1620023      0x00000000fb1fa023
0xfde00030:     0x00000000d1603023      0x00000000d1604023

The third (readable) entry appears to be the recursive page table mapping region:

# ./xenctrl 1 -l3 0xfb046 dump 0xfdfec000 16384
0xfdfec000:      -- page of zeros --   Address space 0x0 - 0x4000.0000
0xfdfed000:      -- page of zeros --   Address space 0x4 - 0x8000.0000
0xfdfee000:      -- page of zeros --   Address space 0x8 - 0xC000.0000
Following are the entries for my kernel's Level 2 Page Directory pages
0xfdfef000:      0xfb041067    0x00000000    0xfb040067    0x00000000
0xfdfef010:      0xfb03f067    0x00000000    0xfb03e067    0x00000000

I.e.: (gdb) x/4x xen_start_info->pt_base
0xc03bb000:     0x00000000fb045001      0x00000000fb044001
0xc03bb010:     0x00000000fb043001      0x00000000fb042001

Below are two page entries to something I can't read:
0xfdfefd60:      0xfbc000e1    0x00000000    0xfba000e1    0x00000000

Below are mappings to: ???
0xfdfefda0:      0x018001e3    0x00000000    0x01a001e3    0x00000000
0xfdfefdb0:      0x01c001e3    0x00000000    0x01e001e3    0x00000000
0xfdfefdc0:      0x020001e3    0x00000000    0x022001e3    0x00000000
0xfdfefdd0:      0x024001e3    0x00000000    0x026001e3    0x00000000
0xfdfefde0:      0x028001e3    0x00000000    0x02a001e3    0x00000000
0xfdfefdf0:      0x02c001e3    0x00000000    0x02e001e3    0x00000000

Below are mappings to the same region above (that I can't read):
0xfdfeff20:      0xfbc001e3    0x00000000    0xfba001e3    0x00000000

Again, more mappings to my page directories:
0xfdfeff60:      0xfb045063    0x00000000    0xfb044063    0x00000000
0xfdfeff70:      0xfb043063    0x00000000    0xfb042063    0x00000000

Mappings to something, but I know not what:
0xfdfeffa0:      0x00224063    0x00000000    0x00225063    0x00000000
0xfdfeffb0:      0x00226063    0x00000000    0x00227063    0x00000000
0xfdfeffc0:      0x00211063    0x00000000    0x00212063    0x00000000
0xfdfeffd0:      0x00213063    0x00000000    0x00214063    0x00000000
0xfdfeffe0:      0x00215063    0x00000000    0x00216063    0x00000000
0xfdfefff0:      0x00217063    0x00000000    0x00bfe063    0x00000000

But, I'm looking for specific documentation regarding these regions.

-- Randy

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