[U-Boot] [PATCH 2/5] Added extra documentation about how the relocation address to RAM is picked for ARM.
Signed-off-by: Christopher Harvey charvey@matrox.com --- doc/README.arm-relocation | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/doc/README.arm-relocation b/doc/README.arm-relocation index 5a9a2fb..954627d 100644 --- a/doc/README.arm-relocation +++ b/doc/README.arm-relocation @@ -22,7 +22,7 @@ At cpu level: modify linker file and add a relocation and fixup loop At board level:
dram_init(): bd pointer is now at this point not accessible, so only - detect the real dramsize, and store it in gd->ram_size. Bst detected + detect the real dramsize, and store it in gd->ram_size. Best detected with get_ram_size().
TODO: move also dram initialization there on boards where it is possible. @@ -38,6 +38,13 @@ At lib level:
Boards which are not fixed to support relocation will be REMOVED!
+The code that picks the location in RAM for ARM can be found in the +arch/arm/lib/board.c file under the board_init_f function. +The postfix _f means executed from flash, and _r means from RAM. +The new location is picked with respect to the highest RAM address, and the +exact final value depends heavily on compile time options. The source is the +best documentation here. + -----------------------------------------------------------------------------
For boards which boot from nand_spl, it is possible to save one copy
Dear Christopher Harvey,
In message 20110704174348.GC3016@harvey-pc.matrox.com you wrote:
Signed-off-by: Christopher Harvey charvey@matrox.com
doc/README.arm-relocation | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)
Please let's stop with ARM specific documatation of things that are considered generic.
+The code that picks the location in RAM for ARM can be found in the +arch/arm/lib/board.c file under the board_init_f function.
under the function? Who dropped that code? :-) s/under/in/
Also delete "for ARM", and s/arm/<arch>/. This is not ARM specific.
+The postfix _f means executed from flash, and _r means from RAM.
Maybe we whould rather write "... from NOR flash" to indicate that we actually mean ROM.
+The new location is picked with respect to the highest RAM address, and the +exact final value depends heavily on compile time options. The source is the +best documentation here.
This should be changed, i. e. better documentation should be provided :-)
Best regards,
Wolfgang Denk
On Mon, Jul 04, 2011 at 09:43:24PM +0200, Wolfgang Denk wrote:
Dear Christopher Harvey,
In message 20110704174348.GC3016@harvey-pc.matrox.com you wrote:
Signed-off-by: Christopher Harvey charvey@matrox.com
doc/README.arm-relocation | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)
Please let's stop with ARM specific documatation of things that are considered generic.
+The code that picks the location in RAM for ARM can be found in the +arch/arm/lib/board.c file under the board_init_f function.
under the function? Who dropped that code? :-) s/under/in/
Also delete "for ARM", and s/arm/<arch>/. This is not ARM specific.
I don't understand, I found the following snippet in arch/arm/lib/board.c
--addr defined and set here--
gd->relocaddr = addr; gd->start_addr_sp = addr_sp; gd->reloc_off = addr - _TEXT_BASE; debug ("relocation Offset is: %08lx\n", gd->reloc_off); memcpy (id, (void *)gd, sizeof (gd_t));
relocate_code (addr_sp, id, addr); /* NOTREACHED - relocate_code() does not return */
Running grep -R gd->relocaddr *, I found similar assignments for various architectures.
... [snip] ...
Best regards,
Wolfgang Denk
Thanks for the clarification, -Chris
Dear Christopher Harvey,
In message 20110706205857.GB2168@harvey-pc.matrox.com you wrote:
Also delete "for ARM", and s/arm/<arch>/. This is not ARM specific.
I don't understand, I found the following snippet in arch/arm/lib/board.c
--addr defined and set here--gd->relocaddr = addr; gd->start_addr_sp = addr_sp; gd->reloc_off = addr - _TEXT_BASE; debug ("relocation Offset is: %08lx\n", gd->reloc_off); memcpy (id, (void *)gd, sizeof (gd_t));
relocate_code (addr_sp, id, addr); /* NOTREACHED - relocate_code() does not return */
Running grep -R gd->relocaddr *, I found similar assignments for various architectures.
Yes, that's what I said: this is not ARM specific, it is supposed to be common code used by all architectures (except for the sad fact that there are several non-conforming implementations). But if we document it, we should document the nominal state. [If in doubt, use the powerpc implementation as reference.]
Best regards,
Wolfgang Denk
participants (3)
-
Albert ARIBAUD -
Christopher Harvey -
Wolfgang Denk