Logical, Linear and Virtual Address.

[Gustavo da Silva]

Good!! Thanks a lot, Denis.

2010/12/23 Denis Kirjanov <kirjanov at gmail.com>:
> On Thu, Dec 23, 2010 at 6:10 PM, Gustavo da Silva
> <gustavodasilva at gmail.com> wrote:
>> Hi Everyone!
>>
>> Friends, could someone explain me the difference between Kernel Logical
>> and Kernel Virtual Address?
>
>
> AFAIK there are 3 types of addresses: physical, kernel virtual
> (one-to-one mapped),
> and ...user virtual addresses...
> Lets assume x86_32 for simplicity:
>
> ==========================
> +kernel part (identity-mapped) +
> ========================== <---- PAGE_OFFSET protection boundary
> +                                          +
> + user portion(THREAD_SIZE)+
> +                                          +
> ==========================
> Kernel works on behalf of the user address space (think about that one
> part of the user space is
> always the same for each process - kernel part). Kernel portion (at
> PAGE_OFFSET and above) translates address
> using simple formula:
> kernel virtual addr - PAGE_OFFSET
>
> Things are different for the bottom half of the virtual address space
> (THREAD_SIZE portion).
> This is a MMU time :)
> Here well-known translation process (using page tables) of the virtual
> address to physical one begins.
>
>> I'm reading Linux Device Drivers 3th, but I did not understand about that.
>>
>> I have a macro vision about Kernel Virtual Address (virtual address is used
>> do hide the paging mechanism and physical memory, I think), and Linear
>> is the address used in to evaluate to the physical (using page
>> directory+page table+offset).
>>
>> But and the Kernel Logical Address? Why Logical Address is Virtual
>> Address, but not all
>> Virtual Address is a Logical Address?
>>
>> Regards.
>>
>> Atenciosamente,
>>
>> Gustavo da Silva
>>
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>>
>
>
>
> --
> Regards,
> Denis
>