ACPI acpi_scan_rsdp() breaks some PCs by not honouring ACPI specification

I am submitting this patch to the kernel linux-acpi mailing list for inclusion in the mainline.

I confirm that this issue is present in Gutsy beta running kernel 2.6.22-12-generic on an Acer TravelMate C102Ti (C100)

Gutsy commit aaed87be2dd4cd3499b092d429e805a50dd797c1

linux-source-2.6.22 (2.6.22-13.40) gutsy; urgency=low

  [Amit Kucheria]

  * Enable CONFIG_VM86 for LPIA
    - LP: #146311
  * Update configuration files
  * Disable MSI by default
  * Add mmconf documentation
  * Update configuration files

  [Bartlomiej Zolnierkiewicz]

  * ide-disk: workaround for buggy HPA support on ST340823A (take 3)
    - LP: #26119

  [Ben Collins]

  * ubuntu/cell: Fixup ps3 related modules for d-i, enable RTAS console
  * ubuntu/cell: Enable CELLEB and related modules (pata_scc)
  * ubuntu/cell: Move ps3rom to storage-core. Also use spidernet, not
    spider_net.
  * ubuntu/cell: Set PS3_MANAGER=y
  * ubuntu: Set NR_CPUS=256 for sparc64-smp

  [Chuck Short]

  * [USB] USB] Support for MediaTek MT6227 in cdc-acm.
    - LP: #134123
  * [XEN] Fix xen vif create with more than 14 guests.
    - LP: #14486

  [Jorge Juan Chico]

  * ide: ST320413A has the same problem as ST340823A
    - LP: #26119

  [Kyle McMartin]

  * fix -rt build
  * fix ia32entry-xen.S for CVE-2007-4573
  * fix build when CONFIG_PCI_MSI is not set

  [Matthew Garrett]

  * hostap: send events on data interface as well as master interface
    - LP: #57146
  * A malformed _GTF object should not prevent ATA device recovery
    - LP: #139079
  * hostap: send events on data interface as well as master interface
    - LP: #57146
  * A malformed _GTF object should not prevent ATA device recovery
    - LP: #139079
  * Don't lose appletouch button release events
  * Fix build with appletouch change
  * Disable Thinkpad backlight support on machines with ACPI video
    - LP: #148055
  * Don't attempt to register a callback if there is no CMOS object
    - LP: #145857
  * Update ACPI bay hotswap code to support locking
    - LP: #148219
  * Update ACPI bay hotswap code to support locking
    - LP: #148219
  * Don't attempt to register a callback if there is no CMOS object
    - LP: #145857
  * Disable Thinkpad backlight support on machines with ACPI video
    - LP: #148055

  [Steffen Klassert]

  * 3c59x: fix duplex configuration
    - LP: #94186

  [Thomas Gleixner]

  * clockevents: remove the suspend/resume workaround^Wthinko

  [Tim Gardner]

  * orinoco_cs.ko missing
    - LP: #125832
  * Marvell Technology ethernet card not recognized and not operational
    - LP: #135316
  * Marvell Technology ethernet card not recognized and not operational
    - LP: #135316
  * acpi_scan_rsdp() breaks some PCs by not honouring ACPI specification
    - LP: #144336
  * VIA southbridge Intel id missing
    - LP: #128289
  * Add T-Sinus 111card to hostap_cs driver to be able to upload firmware
    - LP: #132466
  * RTL8111 PCI Express Gigabit driver r8169 big files produce slow file
    transfer
    - LP: #114171
  * Guest OS does not recognize a lun with non zero target id on Vmware ESX
    Server
    - LP: #140761
  * Modualrize vesafb
    - LP: #139505
  * Nikon cameras need support in unusual_devs.h
    - LP: #134477
  * agp for i830m broken in gutsy
    - LP: #139767
  * hdaps: Added support for Thinkpad T61
    - LP: #147383
  * xen: Update config for i386
    - LP: #139047
  * xen: resync for amd64
    - LP: #139047
  * ide-disk: workaround for buggy HPA support ...