Dotaz: Kernel HIGHMEM4G

[Tomas10]

Zdravim,

ve firme mame server PE2850. puvodne jsem v nem mel 2 moduly 512 MB pameti. O vikendu jsem tyto moduly nahradil dvema uplne stejnymi moduly 2GB . Cili v serveru by mely byt 4GB.

Server nabehl v poradku. Vypis lshw ukazuje  2 moduly po 2GB usazenych ve slotech.

Bohuzel system mi ukazuje, ze je pritomno pouze 890 MB pameti (vypisy top, /proc/meminfo/

Na serveru bezi Debian sarge 3.1.  Kernel je 2.4.27-2-386.  Tento kernel tam je kvuli podpore ovladace megaraid2

Kdyz se podivam na konfiguracni parametry kernelu -

- je zde uvedeno CONFIG_NOHIGHMEM=y
# CONFIG_HIGHMEM4G is not set
# CONFIG_HIGHMEM64G is not set
# CONFIG_HIGHMEM is not set
# CONFIG_DEBUG_HIGHMEM is not set

Otazka - muze toto nastaveni mit vliv na to, ze system bude pracovat pouze s pameti do 1GB ?

 

 

Odpovědi

[mimi.vx]

 Nemuze ..... ono je toho pricinou ,,, defaultne neni highmen zapnut ....

Takze bud prelozit jadro s higmem a nebo prejit na  64bit jadro ale coz ke stari serveru asi nebude mozne .....

[chochi]

Ahoj,

Odpovidajici sekce v KConfigu:

config NOHIGHMEM
    bool "off"
    depends on !X86_NUMAQ
    ---help---
      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!

      The actual amount of total physical memory will either be
      auto detected or can be forced by using a kernel command line option
      such as "mem=256M". (Try "man bootparam" or see the documentation of
      your boot loader (lilo or loadlin) about how to pass options to the
      kernel at boot time.)

      If unsure, say "off".

config HIGHMEM4G
    bool "4GB"
    depends on !X86_NUMAQ
    help
      Select this if you have a 32-bit processor and between 1 and 4
      gigabytes of physical RAM.


config HIGHMEM64G
    bool "64GB"
    depends on !M386 && !M486
    select X86_PAE
    help
      Select this if you have a 32-bit processor and more than 4
      gigabytes of physical RAM.


Takze pro zacatek je potreba zanout CONFIG_HIGHMEM4G, coz umozni pouziti cca 3.5GB, pokud ale chces plnych 4GB tak bud zapnout CONFIG_HIGHMEM64G (zapne podporu PAE), nebo 64bit system.