[U-Boot-Users] _gp and __got_start alignment problem in u-boot.lds

[Burch, John T.]

There seems to be a problem common to several of the mips targets
u-boot.lds files.  I've found that if any code results in data falling
into the .sdata section, there's a good possibility that _gp and
__got_start will not be equal, resulting in u_boot_cmds not being
relocated properly (and ultimately, some/all commands not functioning
properly or at all).

Modifications to the u-boot.lds file appears to have corrected the
problem.
diff -u -r1.1 u-boot.lds
--- u-boot.lds  22 Mar 2006 15:09:07 -0000  1.1
+++ u-boot.lds  26 May 2006 14:30:00 -0000
@@ -46,7 +46,9 @@
    . = ALIGN(4);
    .sdata  : { *(.sdata) }

-   _gp = ALIGN(16);
+   . = ALIGN(16);
+   . = .;
+   _gp = .;

    __got_start = .;
    .got  : { *(.got) }


Here are before and after fragments of u-boot map files:

...before...
.sdata      0x00000000bfc3dd00   0x4
 *(.sdata)
 .sdata     0x00000000bfc3dd00   0x4 common/libcommon.a(main.o)
            0x00000000bfc3dd00           dummy
 *(.sdata)
            0x00000000bfc3dd10           _gp = ALIGN (0x10)
            0x00000000bfc3dd04           __got_start = .   <<<

.got        0x00000000bfc3dd10  0x734
 *(.got)
 .got       0x00000000bfc3dd10  0x734 cpu/mips/start.o
            0x00000000bfc3dd10           _GLOBAL_OFFSET_TABLE_


...after...
.sdata      0x00000000bfc3dd00   0x4
 *(.sdata)
 .sdata     0x00000000bfc3dd00   0x4 common/libcommon.a(main.o)
            0x00000000bfc3dd00           dummy
 *(.sdata)
            0x00000000bfc3dd10           . = ALIGN (0x10)
            0x00000000bfc3dd10           . = .
            0x00000000bfc3dd10           _gp = .
            0x00000000bfc3dd10           __got_start = .   <<<

.got        0x00000000bfc3dd10  0x734
 *(.got)
 .got       0x00000000bfc3dd10  0x734 cpu/mips/start.o
            0x00000000bfc3dd10           _GLOBAL_OFFSET_TABLE_


Has anyone run into this problem?

John
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