Rajaram S wrote:
My question is :
1. Does this mean that irrespective of which process is in kernel
mode, a linear address X will only map to the same physical address Y ?
( Because in user mode, linear address X can map to physical address Y
for process P1, but for another process P2 the same linear address X
will map to another physical address Z. )
yes (for all x > 0xc0000000)
because the kernel directly maps physical memory from 0 to 896MB in its
address space.
2. If so, does this mean two different processes in kernel mode cannot
access the same linear address X ( unless the address maps to common
kernel code or data ) ?
Also when explaining ZONE_DMA , ZONE_NORMAL etc , the author says "The
ZONE_DMA and ZONE_NORMAL zones include the 'normal' page frames that
can be directly accessed by the kernel through the linear mapping in
the fourth gigabyte of the linear address space".
Why only the fourth gigabyte of the linear address space ? Do not the
0-3GB of user mode address space use the page frames of these Zones ?
this might help you to clear your doubts http://kerneltrap.org/node/2450
--
Vivek Kutal
--
To unsubscribe from this list: send an email with
"unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx
Please read the FAQ at http://kernelnewbies.org/FAQ
