[U-Boot-Users] Re: Some puzzles on dram_size()

[SAM SONG]

Hi,Wolfgang,

 --- Wolfgang Denk <wd at denx.de> wrote:
> 
> >in message
> >
<OF5B21F0A5.A3EF40B7ON85256E13.0056838C at nanometrics.ca>>
> you wrote:
> > 
> > Your problem with dram_size() may be that it tests
> > memory beyond the maxsize given.
> 
> No. His max value as defined in the board config
> file was 64 MB, with an actual 16 MB of RAM.

But there are two chips of MT48LC16M16A2
[2*(16*16/8)=64MByte] on LITE_DW.So set SDRAM_MAX_SIZE
as 0x4000000 can match the need of SDRAM_MAX_SIZE.It
should work but crashed.When I set SDRAM_MAX_SIZE as
0x2000000(32MB),it booted normally but the memory
layout didn't look reasonable for u-boot located at
high 128K of 32MB rather than high 128K of actual
RAM.Followings are my test results on LITE_DW.

1.When I set SDRAM_MAX_SIZE as 0x2000000(32MB):

U-Boot 1.0.0 (Jan  7 2004 - 21:13:13)

CPU:   PPC823EZTnnB2 at 64 MHz: 16 kB I-Cache 8 kB
D-Cache
Board: RPXlite
DRAM:  32 MB
FLASH: 16 MB
*** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   SCC ETHERNET
u-boot>
 
But u-boot located at 0x01fe1000.And I could see
0x2000000-0x3ffffff.Meanwhile,it could load linux
kernel and booted.

2.When I changed two lined code as Chris gave and set
SDRAM_MAX_SIZE = 0x4000000(64MB),it worked well.

U-Boot 1.0.0 (Jan  7 2004 - 21:13:13)

CPU:   PPC823EZTnnB2 at 64 MHz: 16 kB I-Cache 8 kB
D-Cache
Board: RPXlite
DRAM:  64 MB
FLASH: 16 MB
*** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   SCC ETHERNET
u-boot>

U-boot located at 0x03fe1000.

3.When I changed two lined code as Chris gave and set
SDRAM_MAX_SIZE = 0x8000000(128MB),it worked badly.

U-Boot 1.0.0 (Jan  7 2004 - 21:22:40)

CPU:   PPC823EZTnnB2 at 64 MHz: 16 kB I-Cache 8 kB
D-Cache
Board: RPXlite
DRAM:  Bus Fault @ 0xff012f4c, fixup 0x00000000
Machine check in kernel mode.
NIP: 01FF1F88 XER: C000B25F LR: 03FE905C REGS:
fa202bc0 TRAP: 1000 DAR: FF010F84
MSR: 00001002 EE: 0 PR: 0 FP: 0 ME: 1 IR/DR: 00

GPR00: 03FE9054 FA202CB0 00000000 03FF683C FA202B88
FA202B78 FFFFFFFE 00000000
GPR08: 00000001 00000000 FA202808 FA2011C8 00000000
00600000 FF020E00 04FE1000
GPR16: FFAC0085 00010001 00900104 40101D41 00001002
FA202CC8 00000000 03FE309C
GPR24: 03FE9000 011C8402 00000001 00000007 FA200100
FA202EC0 04001F60 FA202CD8
Call backtrace:
Software Emulation Exception
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

BDI>re
- TARGET: processing user reset request
- TARGET: resetting target passed
- TARGET: processing target init list ....
- TARGET: processing target init list passed
BDI>g
BDI>i
    Target state      : running
BDI>halt
    Target state      : debug mode
    Debug entry cause : external breakpoint
    Current PC        : 0x03ff5414
BDI>

My conclusion for the RAM-SIZE test code:
1. If the following word is the test code's
purpose,the test code by now still need to fix. 
> Let's put this right: the board config file  is 
> required  to  define SDRAM_MAX_SIZE  greater  than 
> or equal to the maximum RAM size of the system.
2. The RAM-SIZE test code of u-boot-1.0.0 in RPXlite.c
can only work right when the setting of SDRAM_MAX_SIZE
smaller than actual RAM but u-boot locates at high
128k of SDRAM_MAX_SIZE rather than high 128K of actual
RAM.At least on LITE_DW,it work like this.

Best regards,

Sam Song

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