But, that happens in setup_arch(). Do we have any chance to change the CR3 at that moment? Thanks, Neo On Nov 14, 2007 6:00 PM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote: > > On Nov 9, 2007 2:56 PM, Neo Jia <neojia@xxxxxxxxx> wrote: > > hi, > > > > I think the swapper_pg_dir is already loaded in head.S. Why we need to > > load it again? Just a simple 2-level page table. > > > > Thanks, > > Neo > > > > -- > > I would remember that if researchers were not ambitious > > probably today we haven't the technology we are using! > > > > Yes, swapper_pg_dir is already defined in head.S, and then loaded into cr3: > > /* > * Enable paging > */ > movl $swapper_pg_dir-__PAGE_OFFSET,%eax > movl %eax,%cr3 /* set the page table pointer.. */ > movl %cr0,%eax > orl $0x80000000,%eax > movl %eax,%cr0 /* ..and set paging (PG) bit */ > ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */ > 1: > /* Set up the stack pointer */ > lss stack_start,%esp > > But u also must remember that cr3 is loaded with something else > whenever the kernel switches among userspace, kernelspace, and > interrupt context, and ioremap() also changes the cr3 as well, in > order to implement the so-called hardware MMU operation. > -- I would remember that if researchers were not ambitious probably today we haven't the technology we are using! -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
