On 5/21/07, Robert P. J. Day <rpjday@xxxxxxxxxxxxxx> wrote:
i want to clarify some terminology since i'm hearing different explanations from different colleagues and i already know what *i* think is correct. given the (typical) kernel address space in the range 3G-4G, it's safe to say that, on most machines, all of the addresses in that interval are "virtual" addresses which must be mapped somehow to produce the corresponding physical address. but those "virtual" addresses fall into two categories. if the address is simply reduced by the offset of 0xc0000000 (on x86) to produce the physical address, this is what most of the literature refers to as a "logical" address. if, instead, the address has to be mapped through the kernel page tables to perhaps access high memory, this is often described as a "virtual" address.
Right.
in short, while all the addresses in kernel space are technically "virtual" addresses, some of them are the simple offset-based ones which are additionally referred to as "logical" addresses.
That is correct.
is that a fair way to look at it? thanks.
Yes, i think so. Why don't you try explaining small difference between virtual kernel address and user virtual address. That will reduce any ambiguity, which may arise. Thanks --psr
rday p.s. another way to look at it is that logical addresses *must* map to somewhere in the first 1G of RAM, while virtual addresses don't have to. -- ======================================================================== Robert P. J. Day Linux Consulting, Training and Annoying Kernel Pedantry Waterloo, Ontario, CANADA http://fsdev.net/wiki/index.php?title=Main_Page ======================================================================== -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
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