- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

boot: use packed attribute for edd_params* structures and their substructures

The sole purpose of this change is to make sure that sizeof produces
"canonical" sizes for these structures. This is to avoid triggering
bugs in the BIOSes that properly handle only the canonical values of
input length provided to INT 13h AH=48h.
The canonical sizes are: 30 for v2, 66 for v3, etc.
Buggy BIOS code probably looks like:
if (input_length > 30) { /* > v2 */
assume that input length is 66 /* assume v3 or later */
}

This should fix boot problems at least on Supermicro X8DT6 and possibly
on P410i Smart Array Controller (as found in e.g. HP DL360 G7).

Reported by: gnn, np, rstone
Debugged by: rstone
Discussed with: ae, np, rstone
MFC after: 4 days

- Add a new header for the x86 boot code that defines various structures
and constants related to the BIOS Enhanced Disk Drive Specification.
- Use this header instead of magic numbers and various duplicate structure
definitions for doing I/O.
- Use an actual structure for the request to fetch drive parameters in
drvsize() rather than a gross hack of a char array with some magic
size. While here, change drvsize() to only pass the 1.1 version of
the structure and not request device path information. If we want
device path information you have to set the length of the device
path information as an input (along with probably checking the actual
EDD version to see which size one should use as the device path
information is variable-length). This fixes data smashing problems
from passing an EDD 3 structure to BIOSes supporting EDD 4.

Reviewed by: avg
Tested by: Dennis Koegel dk neveragain.de
MFC after: 1 week