[OpenAFS-devel] kernel 2.4.0 and openafs-1.0.2 ...

[Chas Williams]

In message <3A76B197.B596252D@lrz-muenchen.de>,Herbert Huber writes:
>Yep, you are absolutely right! Everything works fine without "high memory
>support".

i am busy with some other projects right now and dont really have time
too look at this, do you really really need config_highmem?  additionally,
what setting were you using?  4 or 64?  btw, i believe that the bug
could be as simple as fixing afs_linux_readpage which does things
the 'old way'--it doesnt use kmap/kunmap.  you know, it took a week to
convince the owner of the intel box i develop on that he needs more
than 64M.

from Configure.help:

High Memory support
CONFIG_NOHIGHMEM
  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
  However, the address space of 32-bit x86 processors is only 4
  Gigabytes large. That means that, if you have a large amount of
  physical memory, not all of it can be "permanently mapped" by the
  kernel. The physical memory that's not permanently mapped is called
  "high memory".

  If you are compiling a kernel which will never run on a machine with
  more than 1 Gigabyte total physical RAM, answer "off" here (default
  choice and suitable for most users). This will result in a "3GB/1GB"
  split: 3GB are mapped so that each process sees a 3GB virtual memory
  space and the remaining part of the 4GB virtual memory space is used
  by the kernel to permanently map as much physical memory as
  possible.

  If the machine has between 1 and 4 Gigabytes physical RAM, then
  answer "4GB" here.

  If more than 4 Gigabytes is used then answer "64GB" here. This
  selection turns Intel PAE (Physical Address Extension) mode on.
  PAE implements 3-level paging on IA32 processors. PAE is fully
  supported by Linux, PAE mode is implemented on all recent Intel
  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
  then the kernel will not boot on CPUs that don't support PAE!