If we are on a loop device, set bsHidden based on the loopback device
offset.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Put the btrfs boot code right after the boot sector (they are really
one image anyway).  Align the ADV with the end of the boot region, so
we can locate it for modification as necessary, and the offset don't
end up shifting with different boot image sizes.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Do the appropriate thing for various error cases, so that the
migration code actually does the right thing.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

- Be able to modify the ADV either in extlinux.sys or ldlinux.sys
- Be able to preserve the ADV from extlinux.sys
- Remove extlinux.sys when installing ldlinux.sys

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

modify_adv() should be used by any installer which uses the common
CLI, so it should go into syslxopt.c.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Install an empty ADV in the Windows installer to keep it from being
broken.  In order to do that, separate the Unix-specific ADV I/O
functions from the generic data structure manipulation.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Merge the SYSLINUX and EXTLINUX patching code and core code, removing
EXTLINUX as a separate derivative.  All the disk-based systems now use
the same code.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Reduce sector 1 space pressure by moving objects that aren't needed by
Sector 1 proper into an "extended patch area".  While we're mucking
with the installer code, make the syslxint and extlinux installer code
even more similar.  It should now be pretty straightforward to
outright merge the code.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Put all the Linux ioctl header magic into a single shared file, and
try to make it as generally useful as possible.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>