Thanks for your response! What is PAGE_OFFSET at 3GB on x86,? As you said PA to VA is found by subtracting PAGE_OFFSET, that means it is not like PA = VA. Right?
On 1/11/08, Mahaveer Darade <[EMAIL PROTECTED]> wrote: > > > > On Jan 11, 2008 10:57 AM, sahlot arvind <[EMAIL PROTECTED]> wrote: > > > Hi All, > > > > I just started learning Linux Virtual Memory Management Subsystem. > > I see the memory is divided into three zones. Comments in file > > mm/mmzone.h > > > > /* > > * ZONE_DMA < 16 MB ISA DMA capable memory > > * ZONE_NORMAL 16-896 MB direct mapped by the kernel > > * ZONE_HIGHMEM > 896 MB only page cache and user processes > > */ > > > > Here second comment (ZONE_NORMAL) says that it is directly mapped by > > kernel. > > Could anybody please tell me what does direct mean here? > > Does this mean Physical address = Virtual Address??? > > > > yes, thats right. > This means any virtual address can be translated to the physical address > by simply subtracting PAGE_OFFSET at 3GB on x86, which is essentially what > the function virt_to_phys() with the macro __pa() does. > > > > > > > > > Thanks > > - Arvind > > > > > > -- > --------------------------- > Thanks & Regards, > Mahaveer Darade > [EMAIL PROTECTED] > Mobile - 9970365267 > > > --- Dream it , Code it. > > ---The "silly question" is the first intimation of some totally new > development
