High Memory problem on 2.4.22 Linux, 2GB ppc card

High Memory problem on 2.4.22 Linux, 2GB ppc card

[Ruksen INANIR]

Hi all,
I am working on a PPC Motorola card, which runs Linux 2.4.22.  The card 
has 2 GB onboard memory. But with use 1456 MB of  the available memory.  
To increase the memory capacity i  need  to  increase the used memory at 
least 64 MB. With CONFIG_HIGHMEM option all of the 2 GB memory can be 
used but, but the fc driver on the card has no high memory support, so 
this caused problems.
  Then i saw that the memory is limited to 1456 by
#define MAX_LOW_MEM        0x5B000000  setting in pgtable.c.  I tried to 
increase it by 64 MB but i could only increase the value of MAX_LOW_MEM 
by 47 MB (1503 MB) without CONFIG_HIGHMEM option.

1)Is there any other setting that i should set other than     
MAX_LOW_MEM to increase the usable memory to 1520 ? Do i need  to 
change  TASK_SIZE or KERNEL_START?
2)I knew that the addressable physical memory without high memory option 
was 1 G.  How was it possible to address 1503 MB without CONFIG_HIGHMEM 
? What is the max usable memory for 2.4.22 kernel?

Thanks,
Rinanir.

Re: High Memory problem on 2.4.22 Linux, 2GB ppc card

[Ruksen INANIR]

I want to change the MAX_LOW_MEM to 1520 MB, what other settings do i 
need to change?  I do not want to use HIGHMEM because the Fiber channel 
does not support highmem. The card is 2 GB ppc. 1520 MB is enough. At 
the moment card works with 1456 MB MAX_LOW_MEM. but setting the value 
MAX_LOW_MEM to 1520 results problems. I believe there should be other 
settings.

Thanks


Ruksen INANIR wrote:
>
> Hi all,
> I am working on a PPC Motorola card, which runs Linux 2.4.22.  The 
> card has 2 GB onboard memory. But with use 1456 MB of  the available 
> memory.  To increase the memory capacity i  need  to  increase the 
> used memory at least 64 MB. With CONFIG_HIGHMEM option all of the 2 GB 
> memory can be used but, but the fc driver on the card has no high 
> memory support, so this caused problems.
>  Then i saw that the memory is limited to 1456 by
> #define MAX_LOW_MEM        0x5B000000  setting in pgtable.c.  I tried 
> to increase it by 64 MB but i could only increase the value of 
> MAX_LOW_MEM by 47 MB (1503 MB) without CONFIG_HIGHMEM option.
>
> 1)Is there any other setting that i should set other than     
> MAX_LOW_MEM to increase the usable memory to 1520 ? Do i need  to 
> change  TASK_SIZE or KERNEL_START?
> 2)I knew that the addressable physical memory without high memory 
> option was 1 G.  How was it possible to address 1503 MB without 
> CONFIG_HIGHMEM ? What is the max usable memory for 2.4.22 kernel?
>
> Thanks,
> Rinanir.