This holds true for phys address 0-896 MB on x86 32 bit Whereas fix mapped linear address is used for things like vmalloc mapping, temporary mapping for atomic page mapping and so on
That means fix-mapped linear addresses are for managing memory in ZONE_HIGHMEM, while just linear addresses are for managing in ZONE_NORMAL? In my pc the size of RAM is 256 MB - does that mean there is no ZONE_HIGHMEM available in my system and all the memory is mapped in ZONE_NORMAL and for dynamic (noncontiguous) allocation of pages ZONE_NORMAL is used? Thanks On 4/28/08, Mulyadi Santosa <[EMAIL PROTECTED]> wrote: > > Let me try.... > > On Sun, Apr 27, 2008 at 7:56 PM, sahlot arvind <[EMAIL PROTECTED]> wrote: > > What is the actual difference between Fix-mapped linear addresses and > linear > > addresses of kernel mapped in the first part of 4th GB of memory? > > Addresses starting from the 4th GB are used for identical mapping... > that is 1 to 1 relationship. Thus, for page at physical address n, it > has a mapping at n+PAGE_OFFSET. This holds true for phys address 0-896 > MB on x86 32 bit > > Whereas fix mapped linear address is used for things like vmalloc > mapping, temporary mapping for atomic page mapping and so on. IMHO it > is said "fix" because it stays on certain predefined range....that is > the upper 128 MB of the 4th GB address space. Again, this is for x86 > 32 bit. > > regards, > > Mulyadi. > -- http://linuxexplained.blogspot.com
