On 3/19/07, Robert P. J. Day <rpjday@xxxxxxxxxxxxxx> wrote:
On Mon, 19 Mar 2007, Daniel Rodrick wrote: > > i'm sure i'm going to embarrass myself with this question, but what > > portion of the kernel address space is set aside for virtual > > addresses? is this fixed? configurable? dynamic? can i see this at > > any time? thanks. > > > > Hi, > > I could not understand clearly. Would appreciate if you could please > elaborate. > > AFAIK, the entire kernel address space (0xC0000000 onwards) is > virtual address space. i probably could have been clearer. a good part of the kernel address space is *logical*, in that it represents simply an offset of the physical address -- low memory starting at physical address 0x0 is mapped to the corresponding logical address starting at (typically) 0xc0000000 on x86. addresses that are mapped via a simple offset are generally referred to as "logical" addresses. but part of that 1G address space has to be reserved for "virtual" addresses that allow the kernel to access physical memory above 1G. so, while all kernel addressing involved "virtual" addresses, i was not including simple logical addresses.
Hi, I think out of the 1 Gb addresses, the first 896 MB is the logical / normal address. And the rest 128 MB are for virtual addresses (returned by vmalloc etc) Thanks, Rajat -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
