Hi Horseriver, On Sun, Feb 24, 2013 at 7:26 AM, horseriver <horserivers@gmail.com> wrote:
On Sun, Feb 24, 2013 at 04:00:37PM +0700, Mulyadi Santosa wrote:
On Sat, Feb 23, 2013 at 6:45 AM, horseriver <horserivers@gmail.com> wrote:
hi:
I have built vmlinux at the top dir of kernel source ,then I use objdump to look into its section information.I find the statup_32 which is the start routine of kernel , locats at 0xc0100000. I know the 0x100000 is the defined address for locating protect-mode code .But which I can not understand is the 0xc prefix .where does it come from?
If my guess is right, that's because kernel mode code start at 0xc000000 a.k.a a bit above 3 GiB on x86 32 bit machine
I have find this answer . It is defined in lds script file .
here is the code : SECTIONS { . = 0xC0000000 + 0x100000; /* read-only */ _text = .; /* Text and read-only data */
why use 0xC0000000 as its start ? why not just use 0x100000 only ? if use 0xC0000000,every linked symbole will be prefixed by 0xc , what is the purpose ?
Usually, user kernel space split is 3G:1G. ie 1G for kernel space. And this starts from 0xC000_0000 till 0xFFFF_FFFF All the address below 0xC000_0000(ie 3G from 0x0 to 0xBFFF_FFFF) is used for user space. Thanks, Arun
thanks!
--
regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies