Address Types in Linux

[Anup Buchke]

Hi all,

I am studying LDD3. It mentions the following types of address which is
creating some confusion.

User Virtual Address : The address space of a process. This ranges from
0-3Gb for 32-bit machines.

Kernel Logical Address : This is the range of address for which there exist
no virtual mapping. They add some offset into the logical address and get
the corresponding physical address. This is also referred as "Low memory."
Kmalloc gives this type of address.

Kernel virtual address : This is the range of address for which virtual
mapping exist. Kernel has to go through the paging mechanism to get the
physical address and then access the location. This is referred as "High
Memory". Vmalloc gives this type of address. If this goes through paging
mechanism...Can there be Page Fault for this type of access?...What kinds
of kernel code/data are placed in "High Memory".

Both Kernel (virtual and logical) address ranges in 3-4GB for 32bit
machines.

Please let me know if this understanding is proper. Also any good comments
to enhance my understanding will be helpful and appreciated.

Thanks

Anup
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