Hi Vamsi,
Le 22/01/2011 05:18, krrish53 a écrit :
Hello everybody, I have a question pertaining to almost every lowlevel_init.S. The code goes like
/*make r0 relative the current location so that it*/ /*reads SMRDATA out of flash rather than memory*/ ldr r0,=SMRDATA ldr r1,_TEXT_BASE sub r10,r0,r1
I couldn't relate the code to comments made ahead of that(how does TEXT_BASE
- addrof(SMRDATA) yield the location of SMRDATA in flash. I totally dint get
it. Please enlighten me. I greatly appreciate any response.
It would be easier if you gave the precise source code origin, filename and location of the code you're mentioning. I took the u-boot-arm current master branch, and could not exactly find any occurrence of "sub r10, r0, r1" so I looked for an appraoching sequence, and found e.g. arch/arm/cpu/arm926ejs/at91/lowlevel_init.S, line 63. Is this what you meant?
/* memory control configuration */ /* this isn't very elegant, but what the heck */ ldr r0, =SMRDATA ldr r1, _MTEXT_BASE sub r0, r0, r1 add r2, r0, #80
If so, the code does not compute TEXT_BASE - SMRDATA, rather the reverse : SMRDATA - TEXT_BASE, .i.e. the relative address of SMRDATA with respect to the image start (depending on START_FROM_MEM, in Flash or physical RAM). I assume #80 is an absolute base address of the actual SMRDATA, but I'm no at91 specialist.
Thanks, Vamsi
Amicalement,