Précisions après 2 mails reçus :
le style devinette du sujet est trompeur, je me pose vraiment la
question, et je n'ai pas la réponse.
La source de mes interrogations : j'ai cherché hier pourquoi une
machine de calcul avec 2 Go de mémoire n'en voyait que 960 Mo.
Réponse dans l'aide de compilation du noyau (2.4.24) :
( cd /usr/src/linux-2.4.24/ ; make menuconfig... )
Menu :
Processor type and features --->
High Memory Support ---> Help
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 960 megabytes of 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.
[...] (si vous voulez voir la suite, regardez par vous même).
Le 2e paragraphe ressemble à une explication sur "pourquoi limiter à 960
Mo / 1 Go", mais je ne la comprends pas.
--
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° /\ Guillaume Allègre Guillaume.Allegre@??? 04.76.51.46.00 p.3539
/~~\/\ Equipe Géométrie Algorithmique / Computational Geometry Team
/ /~~\ Labo. LMC-IMAG Univ. J. Fourier Grenoble France
