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x86: Add RAM bootstrap functionality

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Add a parameter to the 32-bit entry to indicate if entry is from Real
Mode or not. If entry is from Real Mode, execute the destructive 'sizer'
routine to determine memory size as we are booting cold and running in
Flash. If not entering from Real Mode, we are executing a U-Boot image
from RAM and therefore the memory size is already known (and running
'sizer' will destroy the running image)

There are now two 32-bit entry points. The first is the 'in RAM' entry
point which exists at the start of the U-Boot binary image. As such,
you can load u-boot.bin in RAM and jump directly to the load address
without needing to calculate any offsets. The second entry point is
used by the real-to-protected mode switch

This patch also changes TEXT_BASE to 0x6000000 (in RAM). You can load
the resulting image at 0x6000000 and simple go 0x6000000 from the u-boot
prompt

Hopefully a later patch will completely elliminate any dependency on
TEXT_BASE like a relocatable linux kernel (perfect world)

Signed-off-by: Graeme Russ <graeme.russ@gmail.com>
This commit is contained in:
Graeme Russ
2010-04-24 00:05:42 +10:00
committed by Wolfgang Denk
parent 759598f82f
commit 077e1958ca
4 changed files with 43 additions and 12 deletions
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2
board/eNET/config.mk
View File

@@ -21,7 +21,7 @@
# MA 02111-1307 USA
#
TEXT_BASE = 0x38040000
TEXT_BASE = 0x06000000
CFLAGS_common/dlmalloc.o += -Wa,--no-warn -fno-strict-aliasing
PLATFORM_RELFLAGS += -fvisibility=hidden
PLATFORM_CPPFLAGS += -fno-dwarf2-cfi-asm

9
board/eNET/u-boot.lds
View File

@@ -27,7 +27,7 @@ ENTRY(_start)
SECTIONS
{
. = 0x38040000; /* Location of bootcode in flash */
. = 0x06000000; /* Location of bootcode in flash */
_i386boot_text_start = .;
.text : { *(.text); }
@@ -97,14 +97,13 @@ SECTIONS
* at reset and the code have to fit.
* The fff0 offset of resetvec is important, however.
*/
. = 0xfffffe00;
.start32 : AT (0x3807fe00) { *(.start32); }
.start32 : AT (0x0603fe00) { *(.start32); }
. = 0xf800;
.start16 : AT (0x3807f800) { *(.start16); }
.start16 : AT (0x0603f800) { *(.start16); }
. = 0xfff0;
.resetvec : AT (0x3807fff0) { *(.resetvec); }
.resetvec : AT (0x0603fff0) { *(.resetvec); }
_i386boot_end = (LOADADDR(.resetvec) + SIZEOF(.resetvec) );
}