summaryrefslogtreecommitdiffstats
path: root/qemu/roms/u-boot/doc/README.TPL
diff options
context:
space:
mode:
authorYang Zhang <yang.z.zhang@intel.com>2015-08-28 09:58:54 +0800
committerYang Zhang <yang.z.zhang@intel.com>2015-09-01 12:44:00 +0800
commite44e3482bdb4d0ebde2d8b41830ac2cdb07948fb (patch)
tree66b09f592c55df2878107a468a91d21506104d3f /qemu/roms/u-boot/doc/README.TPL
parent9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (diff)
Add qemu 2.4.0
Change-Id: Ic99cbad4b61f8b127b7dc74d04576c0bcbaaf4f5 Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Diffstat (limited to 'qemu/roms/u-boot/doc/README.TPL')
-rw-r--r--qemu/roms/u-boot/doc/README.TPL45
1 files changed, 45 insertions, 0 deletions
diff --git a/qemu/roms/u-boot/doc/README.TPL b/qemu/roms/u-boot/doc/README.TPL
new file mode 100644
index 000000000..980debe77
--- /dev/null
+++ b/qemu/roms/u-boot/doc/README.TPL
@@ -0,0 +1,45 @@
+Generic TPL framework
+=====================
+
+Overview
+--------
+
+TPL---Third Program Loader.
+
+Due to the SPL on some boards(powerpc mpc85xx) has a size limit and cannot
+be compatible with all the external device(e.g. DDR). So add a tertiary
+program loader (TPL) to enable a loader stub loaded by the code from the
+SPL. It loads the final uboot image into DDR, then jump to it to begin
+execution. Now, only the powerpc mpc85xx has this requirement and will
+implemente it.
+
+Keep consistent with SPL, with this framework almost all source files for a
+board can be reused. No code duplication or symlinking is necessary anymore.
+
+How it works
+------------
+
+There has been a directory $(srctree)/spl which contains only a Makefile. The
+Makefile is shared by SPL and TPL.
+
+The object files are built separately for SPL/TPL and placed in the
+directory spl/tpl. The final binaries which are generated are
+u-boot-{spl|tpl}, u-boot-{spl|tpl}.bin and u-boot-{spl|tpl}.map.
+
+During the TPL build a variable named CONFIG_TPL_BUILD is exported in the
+make environment and also appended to CPPFLAGS with -DCONFIG_TPL_BUILD.
+
+The SPL options are shared by SPL and TPL, the board config file should
+determine which SPL options to choose based on whether CONFIG_TPL_BUILD
+is set. Source files can be compiled for TPL with options choosed in the
+board config file.
+
+For example:
+
+spl/Makefile:
+LIBS-$(CONFIG_SPL_LIBCOMMON_SUPPORT) += common/libcommon.o
+
+CONFIG_SPL_LIBCOMMON_SUPPORT is defined in board config file:
+#ifdef CONFIG_TPL_BUILD
+#define CONFIG_SPL_LIBCOMMON_SUPPORT
+#endif