High Memory problem on 2.4.22 Linux, 2GB ppc card

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 ?
    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.

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 ?
   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.