MPC5566 MMU Initialization Debug?

beau_l_peacock — Thu, 23 May 2019 14:37:34 GMT

Hello,

I am looking into getting help to understand how to debug/probe the MMU initialization?

NXP IC: MPC5566

CodeWarrior IDE version 5.9.0

To be honest I don't even know if I can even ask a good question. I am attempting to follow the complete boot up of the MPC5566 and I don't know how to step through any startup sequence for the MMU.

First step I do is create a new project using the code warriors wizard to setup the project.

Code warrior creates a project explorer as follows. I believe the MMU and the TLBs need to be configured prior to most of the operation of the chip. The only location that I find this is in MPC_HWInit.c

/*----------------------------------------------------------------------------*/
/* Writing to MMU Table Entries */
/*----------------------------------------------------------------------------*/

/* Write one MMU Table Entry: */
/* r3, r4, r5 and r6 must hold */
/* the values of MAS0, MAS1, MAS2 and MAS3 */
__asm void WriteMMUTableEntry( void )
{
nofralloc

/* Write MMU Assist Register 0 (MAS0); SPR 624 */
mtspr 624, r3
/* Write MMU Assist Register 1 (MAS1); SPR 625 */
mtspr 625, r4
/* Write MMU Assist Register 2 (MAS2); SPR 626 */
mtspr 626, r5
/* Write MMU Assist Register 3 (MAS3); SPR 627 */
mtspr 627, r6
/* Write the table entry */
tlbwe

blr
}

But I can't figure out how this __asm function is called? My guess is that they are called during boot up by placing them in memory prior to main file. Looking into the linker configuration file, MPC5566.lcf I see.

SECTIONS
{
.__bam_bootarea LOAD (0x00000000): {} > resetvector

GROUP : {
.init LOAD (0x00000020) : {}
.init_vle (VLECODE) LOAD (_e_init) : {
*(.init)
*(.init_vle)
}
} > init

.__exception_handlers (VLECODE) LOAD (0x00001000): {} > exception_handlers

GROUP : {
.text : {}
.text_vle (VLECODE) ALIGN(0x1000): {
*(.text)
*(.text_vle)
}
.rodata (CONST) : {
*(.rdata)
*(.rodata)
}
.ctors : {}
.dtors : {}
extab : {}
extabindex : {}
} > internal_flash

GROUP : {
.__uninitialized_intc_handlertable ALIGN(0x10) : {}
.data : {}
.sdata : {}
.sbss : {}
.sdata2 : {}
.sbss2 : {}
.bss : {}
} > internal_ram
}

Where an init (I am assuming this is Startup Code files) group is before the internal flash .text (which I am assuming is the main function). If this is the case how do I know what order any of the Startup files are going in?

Thanks for any help anyone can provide.

Re: MPC5566 MMU Initialization Debug?

lukaszadrapa — Tue, 28 May 2019 07:59:04 GMT

Hi Beau,

if default settings performed by BAM are sufficient for you, you do not need to change it:

Function WriteMMUTableEntry is used in startup files only when using external memory. Note from the reference manual:

You can find this code in MPC5566_HWInit.c file:

This is also example which shows how to call the function.

This excel tool can help to modify the MMU if you really need it:

https://community.nxp.com/docs/DOC-331924

The best way to see what kind of operation is done in startup files is to step them step by step.

Regards,

Lukas

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