Change in coreboot[master]: cpu/qemu-x86: Add x86_64 bootblock support

[Patrick Rudolph (Code Review)]

Hello Kyösti Mälkki, Aaron Durbin, Alexandru Gagniuc, ron minnich, Gerd Hoffmann, Lee Leahy, Stefan Reinauer, build bot (Jenkins), Patrick Georgi, Martin Roth,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/35680

to look at the new patch set (#7).

Change subject: cpu/qemu-x86: Add x86_64 bootblock support
......................................................................

cpu/qemu-x86: Add x86_64 bootblock support

Add support for x86_64 bootblock on qemu.

Introduce a new approach to long mode support. The previous patch set
generated page tables at runtime and placed them in heap. The new
approach places the page tables in memory mapped ROM.

Introduce a new tool called pgtblgen that creates x86 long mode compatible
page tables and writes those to a file. The file is included into the CBFS
and placed at a predefined offset.

Add assembly code to load the page tables, based on a Kconfig symbol and
enter long in bootblock.

The code can be easily ported to real hardware bootblock.

Tested on qemu q35.

Change-Id: Iec92c6cea464c97c18a0811e2e91bc22133ace42
Signed-off-by: Patrick Rudolph 
---
M Documentation/arch/x86/index.md
M Makefile.inc
M src/arch/x86/Kconfig
M src/arch/x86/bootblock_crt0.S
M src/cpu/qemu-x86/cache_as_ram_bootblock.S
A src/cpu/x86/64bit/entry64.inc
A util/pgtblgen/Makefile.inc
A util/pgtblgen/description.md
A util/pgtblgen/pgtblgen.c
9 files changed, 297 insertions(+), 12 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/80/35680/7