On 14-06-10 11:45 PM, Albert ARIBAUD wrote:
Hi Wolfgang,
On Wed, 11 Jun 2014 06:49:28 +0200, Wolfgang Denk wd@denx.de wrote:
Dear Steve,
In message 53979199.5010100@broadcom.com you wrote:
OK - I think that one of the alternate proposals would be to conditionally reserve a "32 byte block" prior to the _start symbol (in "arch/arm/cpu/armv8/start.S") which would then be filled in by a post-processing step... This could be implemented by:
Yes, that illustrates the idea. However, this implementation suffers from the use of an #ifdef where none is actually needed. Instead, you can create your own source file which defines the header; this could be then even in it's own segment, say:
your_header.c:
struct your_header { u_int32[8]; } your_header __attribute__ ((__section__ (".your_hdr")));
All that is needed then is to make the linker place this segment in front of the text segment.
This avoids an ugly #ifdef, and also modifications in the common code.
Agreed and seconded.
Plus, using a dedicated 'header' section and a separate C source file for the header makes it automatic that if no input 'header' section were provided then no output 'header' section would be emitted; IOW, we would not need two different linker scripts, a single one would be useable for both 'headerless' and 'headerful' image types.
Also, the alignment constraint should be configurable.
Best regards,
Wolfgang Denk
Amicalement,
Albert, Wolfgang, et al.
I didn't know about the automatic handling of "conditional" sections in the linker script file - Thanks!!!
So if I add a "your_header.c" as above, then
(1) I need to modify "arch/arm/cpu/armv8/u-boot.lds": . = 0x00000000;
+ . = ALIGN(8); + .your_hdr : { + KEEP(*(.your_hdr*)); + } + . = ALIGN(8); .text : {
(2) then (I believe) I need to modify the "Makefile" to define the start address of this new section: +LDFLAGS_u-boot += --section-start=".your_hdr"=CONFIG_YOUR_HEADER_ADDR
(3) and (I believe) I need to modify the OBJCOPYFLAGS (somewhere) in order to include this new section in the u-boot.bin: +OBJCOPYFLAGS += -j .your_hdr
(... I don't actually have this working yet; so I suspect more changes are required ...)
And in the end, (I believe) I am just going to have a block (likely 4096 bytes) prepended to the "original" u-boot.bin; which I can do today with no code changes at all....
Remember that original design request was effectively a two line change: + gd->mon_len += CONFIG_SYS_TEXT_BASE % 4096; and + gd->relocaddr += CONFIG_SYS_TEXT_BASE % 4096;
Regrettably, since this is not going to be accepted, I am abandoning this change. Thanks, Steve