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-rw-r--r--doc/README.x8632
1 files changed, 21 insertions, 11 deletions
diff --git a/doc/README.x86 b/doc/README.x86
index af2459c..9012541 100644
--- a/doc/README.x86
+++ b/doc/README.x86
@@ -18,15 +18,16 @@ U-Boot supports running as a coreboot [1] payload on x86. So far only Link
work with minimal adjustments on other x86 boards since coreboot deals with
most of the low-level details.
-U-Boot also supports booting directly from x86 reset vector without coreboot,
-aka raw support or bare support. Currently Link, QEMU x86 targets and all
-Intel boards support running U-Boot 'bare metal'.
+U-Boot also supports booting directly from x86 reset vector, without coreboot.
+In this case, known as bare mode, from the fact that it runs on the
+'bare metal', U-Boot acts like a BIOS replacement. Currently Link, QEMU x86
+targets and all Intel boards support running U-Boot 'bare metal'.
As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
Linux kernel as part of a FIT image. It also supports a compressed zImage.
-Build Instructions
-------------------
+Build Instructions for U-Boot as coreboot payload
+-------------------------------------------------
Building U-Boot as a coreboot payload is just like building U-Boot for targets
on other architectures, like below:
@@ -48,6 +49,8 @@ Change the 'Board configuration file' and 'Board Device Tree Source (dts) file'
to point to a new board. You can also change the Cache-As-RAM (CAR) related
settings here if the default values do not fit your new board.
+Build Instructions for U-Boot as BIOS replacement (bare mode)
+-------------------------------------------------------------
Building a ROM version of U-Boot (hereafter referred to as u-boot.rom) is a
little bit tricky, as generally it requires several binary blobs which are not
shipped in the U-Boot source tree. Due to this reason, the u-boot.rom build is
@@ -58,7 +61,9 @@ $ export BUILD_ROM=y
This tells the Makefile to build u-boot.rom as a target.
-Link-specific instructions:
+---
+
+Chromebook Link specific instructions for bare mode:
First, you need the following binary blobs:
@@ -87,7 +92,9 @@ Now you can build U-Boot and obtain u-boot.rom:
$ make chromebook_link_defconfig
$ make all
-Intel Crown Bay specific instructions:
+---
+
+Intel Crown Bay specific instructions for bare mode:
U-Boot support of Intel Crown Bay board [4] relies on a binary blob called
Firmware Support Package [5] to perform all the necessary initialization steps
@@ -122,7 +129,9 @@ Now you can build U-Boot and obtain u-boot.rom
$ make crownbay_defconfig
$ make all
-Intel Minnowboard Max instructions:
+---
+
+Intel Minnowboard Max instructions for bare mode:
This uses as FSP as with Crown Bay, except it is for the Atom E3800 series.
Download this and get the .fd file (BAYTRAIL_FSP_GOLD_003_16-SEP-2014.fd at
@@ -188,8 +197,9 @@ Offset Description Controlling config
Overall ROM image size is controlled by CONFIG_ROM_SIZE.
+---
-Intel Galileo instructions:
+Intel Galileo instructions for bare mode:
Only one binary blob is needed for Remote Management Unit (RMU) within Intel
Quark SoC. Not like FSP, U-Boot does not call into the binary. The binary is
@@ -252,8 +262,8 @@ At present it seems that for Minnowboard Max, coreboot does not pass through
the video information correctly (it always says the resolution is 0x0). This
works correctly for link though.
-Test with QEMU
---------------
+Test with QEMU for bare mode
+----------------------------
QEMU is a fancy emulator that can enable us to test U-Boot without access to
a real x86 board. Please make sure your QEMU version is 2.3.0 or above test
U-Boot. To launch QEMU with u-boot.rom, call QEMU as follows: