P1022 TLB entries

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sujanathinaraya
Contributor II

Hi, 

         I am working on P1022 board. In that tlb.c file, I have seen below TLB0 entries ( CONFIG_SYS_INIT_RAM_ADDR - 0xffd00000,  size - 16K) .please explain me  the pupose of this 16K temp stack in cache.

/* TLB 0 - for temp stack in cache */
 SET_TLB_ENTRY(0, CONFIG_SYS_INIT_RAM_ADDR, CONFIG_SYS_INIT_RAM_ADDR,
 MAS3_SX|MAS3_SW|MAS3_SR, 0,
 0, 0, BOOKE_PAGESZ_4K, 0),
 SET_TLB_ENTRY(0, CONFIG_SYS_INIT_RAM_ADDR + 4 * 1024,
 CONFIG_SYS_INIT_RAM_ADDR + 4 * 1024,
 MAS3_SX|MAS3_SW|MAS3_SR, 0,
 0, 0, BOOKE_PAGESZ_4K, 0),
 SET_TLB_ENTRY(0, CONFIG_SYS_INIT_RAM_ADDR + 8 * 1024,
 CONFIG_SYS_INIT_RAM_ADDR + 8 * 1024,
 MAS3_SX|MAS3_SW|MAS3_SR, 0,
 0, 0, BOOKE_PAGESZ_4K, 0),
 SET_TLB_ENTRY(0, CONFIG_SYS_INIT_RAM_ADDR + 12 * 1024,
 CONFIG_SYS_INIT_RAM_ADDR + 12 * 1024,
 MAS3_SX|MAS3_SW|MAS3_SR, 0,
 0, 0, BOOKE_PAGESZ_4K, 0),
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ufedor
NXP Employee
NXP Employee

Please consider that CONFIG_SYS_INIT_RAM_ADDR is:

Start address of memory area that can be used for initial data and stack; please note that this must be writable memory that is working WITHOUT special initialization, i. e. you CANNOT use normal RAM which will become available only after programming the memory controller and running certain initialization sequences.

Refer to the Start.s:

u-boot/start.S at b3f98d438eefd1b355efdec0b50af5813ff8d0e1 · qoriq-open-source/u-boot · GitHub 

/* L1 DCache is used for initial RAM */

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sujanathinaraya
Contributor II

Hi,

Thank you ufedor for your valuable reply. I understand that CONFIG_SYS_INIT_RAM_ADDR is configured as L1 data cache to  execute program before initialization of normal ram. Whether CONFIG_SYS_INIT_RAM_ADDR address and size is configurable? i.e any address and size can be used instead of 0xffd00000 and 16k  size.  

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ufedor
NXP Employee
NXP Employee

any address and size can be used instead of 0xffd00000 and 16k  size.  

The address should not interfere with the final memory map.

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sujanathinaraya
Contributor II

How this address is configured as L1 data cache address? 

More than 32kb size can i configure? 

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ufedor
NXP Employee
NXP Employee

How this address is configured as L1 data cache address? 

Refer to the "Start.s" code.

More than 32kb size can i configure? 

Of course - not.

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sujanathinaraya
Contributor II

Thank you ufedor...

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ufedor
NXP Employee
NXP Employee

Please consider that CONFIG_SYS_INIT_RAM_ADDR is:

Start address of memory area that can be used for initial data and stack; please note that this must be writable memory that is working WITHOUT special initialization, i. e. you CANNOT use normal RAM which will become available only after programming the memory controller and running certain initialization sequences.

Refer to the Start.s:

u-boot/start.S at b3f98d438eefd1b355efdec0b50af5813ff8d0e1 · qoriq-open-source/u-boot · GitHub 

/* L1 DCache is used for initial RAM */

2,560件の閲覧回数
sujanathinaraya
Contributor II

Thank you ufedor for your valuable reply. I understand that CONFIG_SYS_INIT_RAM_ADDR is configured as L1 data cache to  execute program before initialization of normal ram. Whether CONFIG_SYS_INIT_RAM_ADDR address and size is configurable? i.e any address and size can be used instead of 0xffd00000 and 16k  size.  

 

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