How is . = 0xADDR different from using MEMORY?
Mike Frysinger
vapier@gentoo.org
Fri Nov 2 01:18:00 GMT 2007
On Thursday 01 November 2007, Rick Mann wrote:
> Hi. I've been trying to move from using . = 0xABCD1234 in my linker
> script to put sections in the right place, to using the MEMORY
> command. But it's not behaving as I would expect.
>
> I have the following sections in the (working) script (there are more,
> but this should serve for the example):
>
> SECTIONS
> {
> . = 0x80008000;
>
> . = ALIGN(4);
> .text :
> {
> obj/start.o(.text);
> src/Interrupts.o(.text);
>
> . = ALIGN(4);
> __gVectorsStart = .;
> KEEP (obj/vectors.o(.text));
> __gVectorsEnd = .;
>
> . = ALIGN(4);
> *(.text);
> }
>
> . = ALIGN(4);
> .bss :
> {
> __bss_start = .;
> __bss_start__ = .;
> /* first the real BSS data */
> *(.bss)
> *(COMMON)
>
> /* and next the stack */
> . = ALIGN(4);
>
> /* allocate an 8kB stack */
> . = . + 8 * 1024;
>
> __stack_end = .;
> __bss_end = .;
> __bss_end__ = .;
> }
>
> . = ALIGN(1024 * 1024);
>
> .frameBuffer :
> {
> __gFrameBufferSectionStart = .;
> *(.frameBuffer)
> __gFrameBufferSectionEnd = .;
> }
>
> . = ALIGN(16 * 1024 * 1024);
>
> .mmuTables :
> {
> *(.mmuTables)
> }
>
> }
>
>
>
> If I do this, I get what I would expect: a 16MB+-sized binary (because
> of the 16MB alignment of .mmuTables). If instead, I add this:
>
> MEMORY
> {
> dram (wx) : org = 0x80008000, len = 128M
>
> vectors (wx) : org = 0x00000000, len = 1M
> theCaddo (wx) : org = 0x5C000000, len = 32K
> bootRomData (rw) : org = 0x5C008000, len = 48K
> sram (wx) : org = 0x5C014000, len = 688K
> rom (rw) : org = 0x5E000000, len = 64K
> monitor (rwx) : org = 0x80000000, len = 32K
>
> }
>
> and append ">dram" to each section above, and remove the . =
> 0x80008000 at the top, I get a 4 MB+ binary.
when you say "binary", do you mean ELF or binary ?
> This is all in an effort to place my sections closer together in the
> image, but I'm not there yet. I just wanted to get the memory map part
> working correctly. Any idea what's going on?
review the LMA's and VMA's as reported by `readelf -l`
-mike
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