Re: [U-Boot-Users] memsize.c patch

2 Apr 2004

      Hi,
You are right.
Sorry for the wrong arguing.
Actually I was debugging my code(board/etin/debris/debrs.c) from old version
of u-boot.
Because I found some problem of my initdram.
After I fixed the problem I found that u-boot gets to use the simular code.
And asumed that u-boot has the same problem.
The difference was this.
My code :  for (cnt = 1; cnt <= CFG_MAX_RAM_SIZE / sizeof(long); cnt <<= 1)
u-boot : for (cnt = 1; cnt < maxsize / sizeof (long); cnt <<= 1)
Isn't it fun?
Regards,
Sangmoon Kim
----- Original Message -----
From: "Sangmoon Kim" dogoil@etinsys.com
To: "Wolfgang Denk" wd@denx.de
Cc: u-boot-users@lists.sourceforge.net
Sent: Friday, April 02, 2004 6:25 PM
Subject: Re: [U-Boot-Users] memsize.c patch
...
Hi,
...
This is intentional. You can  only  find  out  how  much  mempory  is
installed  when  you test beyound the end - otrherwise there might be
more memory, right? You must map more memory, then.
I know this is intentional.
But in case of MPC8245 which has 4 DBATs.
We need one DBAT for DCACHE, one for PCI  and one for Flash.
Then there is only one DBAT left for SDRAM.
The maximum size of DBAT is 256M bytes.
So the maximum capacity of SDRAM that u-boot can handle is 256M bytes.
Now if the CFG_MAX_RAM_SIZE is set to 256M and 256M SDRAM is installed,
the get_ram_size routine tries to read some value at (base + 0x10000000)
which is outside of block address translation.
Then the board hangs.
The patch fixes the problem.
...
Just a simple question: what happens if base != 0 ?
I forgot that.
Then how about this.
    for (cnt = 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
            addr = base + cnt;      /* pointer arith! */

          val = *addr;

          *addr = save[--i];

          if (val != ~cnt) {

          if (addr < (base + maxsize)) {

                  val = *addr;

                  *addr = save[--i];

          }

          if ((val != ~cnt) || (addr >= base + maxsize)) {

Regards,
Sangmoon Kim

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