ide: preserve Host Protected Area by default (v2)

From the perspective of most users of recent systems, disabling Host
Protected Area (HPA) can break vendor RAID formats, GPT partitions and
risks corrupting firmware or overwriting vendor system recovery tools.

Unfortunately the original (kernels < 2.6.30) behavior (unconditionally
disabling HPA and using full disk capacity) was introduced at the time
when the main use of HPA was to make the drive look small enough for the
BIOS to allow the system to boot with large capacity drives.

Thus to allow the maximum compatibility with the existing setups (using
HPA and partitioned with HPA disabled) we automically disable HPA if
any partitions overlapping HPA are detected.  Additionally HPA can also
be disabled using the "nohpa" module parameter (i.e. "ide_core.nohpa=0.0"
to disable HPA on /dev/hda).

v2:
Fix ->resume HPA support.

While at it:
- remove stale "idebus=" entry from Documentation/kernel-parameters.txt

Cc: Robert Hancock <hancockrwd@gmail.com>
Cc: Frans Pop <elendil@planet.nl>
Cc: "Andries E. Brouwer" <Andries.Brouwer@cwi.nl>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
[patch description was based on input from Alan Cox and Frans Pop]
Emphatically-Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a19f021f081a..e58c91ca802c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -835,11 +835,8 @@ and is between 256 and 4096 characters. It is defined in the file
 
         ide-core.nodma= [HW] (E)IDE subsystem
                         Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
-                        .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
-                        .chs .ignore_cable are additional options
-                        See Documentation/ide/ide.txt.
-
-        idebus=         [HW] (E)IDE subsystem - VLB/PCI bus speed
+                        .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
+                        .cdrom .chs .ignore_cable are additional options
                         See Documentation/ide/ide.txt.
 
         ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem