Re: HIGHMEM

["Hdei Nunoe" <nunoe@co-nss.co.jp>]

Ralf,

It worked fine with small changes!!   Comment and Criticism are welcome.

>> >Other than that you can also just setup your system
>> >as 0x0 - 0x10000000 being RAM, 0x10000000 - 0x20000000 being reserved
>> >memory and 0x20000000 - 0x30000000 being highmem.  Which works but is a
>> >bit wasteful.

I have set up my system as following :
- 0x00000000 - 0x10000000 RAM
- 0x10000000 - 0x40000000 RESERVED
- 0x40000000 - 0x50000000 RAM
So that the gap in physical address space and one in virtual address space 
becomes equal.
It is 0x40000000 in this case (0x10000000 - 0x40000000 vs 0x90000000 - 
0xc0000000).
That means no physical <-> virtual macro change are needed.  hehe...
And the MMU mapping to the upper 256MB is fixed with the CP0 wired register.

Changes are pretty small as follows :
--- tlb-r4k.c ---
381c381
<       write_32bit_cp0_register(CP0_WIRED, 0);
---
>       write_32bit_cp0_register(CP0_WIRED, 8 /* XXX 0 */);

--- pgtable.h ---
123c123
< #define VMALLOC_START     KSEG2
---
> #define VMALLOC_START     KSEG3               /* XXX KSEG2 */

--- page.h ---
148c148
< #define HIGHMEM_START 0x20000000UL
---
> #define HIGHMEM_START 0x50000000UL    /* XXX 0x20000000UL */

--- prom.c ---
>       add_memory_region(0, (256*1024*1024), BOOT_MEM_RAM);
>       add_memory_region(0x10000000, (256*1024*1024), BOOT_MEM_RESERVED);
>       add_memory_region(0x20000000, (512*1024*1024), BOOT_MEM_RESERVED);
>       add_memory_region(0x40000000, (256*1024*1024), BOOT_MEM_RAM);
>
>       {
>           TLB_TBL32 tlb;
>           unsigned int nTlb = 48;             /* max TLB entry */
>           unsigned int size = 0x02000000;     /* 32MB boundary */
>           unsigned int vadr = 0xc0000000;     /* virtual address */
>           unsigned int padr = 0x40000000;     /* physical address */
>
>           printk ("memory map started.\n");
>             for (i=0; i<8; i++)
>               {
>               tlb.mask = 0x01ffe000;          /* 16M bit[24-13] */
>               tlb.hi  = vadr + (i*size);
>               tlb.lo1 = (padr >> 6) | ((i*size + (size/2)) >> 6) | 0x1f;
>               tlb.lo0 = (padr >> 6) | ((i*size) >> 6) | 0x1f;
>               setTLB32 (i, &tlb);
>               }
>             for (i=8; i<nTlb; i++)
>               {
>               tlb.mask = 0x0;
>               tlb.hi  = 0x80000000;
>               tlb.lo1 = 0;
>               tlb.lo0 = 0;
>               setTLB32 (i, &tlb);
>               }
>             for (i=0; i<nTlb; i++)
>               {
>               getTLB32 (i, &tlb);
>               printk ("get: mask=0x%08x hi=0x%08x lo0=0x%08x 
> lo1=0x%08x.\n",
>                       tlb.mask, tlb.hi, tlb.lo0, tlb.lo1);
>               }
>       }

Cheers,
-hdei