Re: relocatable modules' symbols
what linear address is the virtual address 0xc000 respondable to ?
the highest 10 bits 0x300 is pde , which means the 0x300th entry of
the page dir.
As I know ,at boot stage , that pde has not been ever filles . then
how does the
kernel code been addressed?
2013/3/1 Prabhu nath :
> In principle, the linker will associate the kernel code/data to the Kernel
> virtual address space i.e. between 0xC000_ to 0x_ and
> the same linker will associate the Application's code/data to the user
> virtual address space i.e. between 0x_ to 0xBFFF_.
>
> Linker itself cannot distinguish between the kernel code/data and user
> code/data but it is the linker script that will guide the linker to
> associate the code/data to the respective addresses.
>
> What you are seeing is the linker script provided to the linker with -T
> option when building the kernel.
>
> To build the user application the linker uses its default linker script
> which you get it by executing
> $ ld --verbose.
>
> To compare between the two just juxtapose the readelf output of both kernel
> executable (vmlinux) and any user application executable (a.out)
>
> $ readelf -a vmlinux
> $ readelf -a a.out
>
> Just inspect the section header and program header of both the outputs you
> will get the difference.
>
> Regards,
> Prabhu
>
>
>
> On Fri, Mar 1, 2013 at 11:07 AM, Arun KS wrote:
>>
>> Hi Horseriver,
>>
>> On Sun, Feb 24, 2013 at 7:26 AM, horseriver wrote:
>> > On Sun, Feb 24, 2013 at 04:00:37PM +0700, Mulyadi Santosa wrote:
>> >> On Sat, Feb 23, 2013 at 6:45 AM, horseriver
>> >> 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 0xc010. I know the 0x10 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
>> >> 0xc00 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
>> > {
>> > . = 0xC000 + 0x10;
>> > /* read-only */
>> > _text = .;/* Text and read-only data */
>> >
>> >
>> > why use 0xC000 as its start ? why not just use 0x10 only ?
>> > if use 0xC000,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_ till 0x_
>>
>> All the address below 0xC000_(ie 3G from 0x0 to 0xBFFF_) 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
>>
>> ___
>> Kernelnewbies mailing list
>> Kernelnewbies@kernelnewbies.org
>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
>
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: relocatable modules' symbols
In principle, the linker will associate the kernel code/data to the Kernel
virtual address space i.e. between 0xC000_ to 0x_ and
the same linker will associate the Application's code/data to the user
virtual address space i.e. between 0x_ to 0xBFFF_.
Linker itself cannot distinguish between the kernel code/data and user
code/data but it is the linker script that will guide the linker to
associate the code/data to the respective addresses.
What you are seeing is the linker script provided to the linker with -T
option when building the kernel.
To build the user application the linker uses its default linker script
which you get it by executing
$ ld --verbose.
To compare between the two just juxtapose the readelf output of both kernel
executable (vmlinux) and any user application executable (a.out)
$ readelf -a vmlinux
$ readelf -a a.out
Just inspect the section header and program header of both the outputs you
will get the difference.
Regards,
Prabhu
On Fri, Mar 1, 2013 at 11:07 AM, Arun KS wrote:
> Hi Horseriver,
>
> On Sun, Feb 24, 2013 at 7:26 AM, horseriver wrote:
> > On Sun, Feb 24, 2013 at 04:00:37PM +0700, Mulyadi Santosa wrote:
> >> On Sat, Feb 23, 2013 at 6:45 AM, horseriver
> 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 0xc010. I know the 0x10 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
> >> 0xc00 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
> > {
> > . = 0xC000 + 0x10;
> > /* read-only */
> > _text = .;/* Text and read-only data */
> >
> >
> > why use 0xC000 as its start ? why not just use 0x10 only ?
> > if use 0xC000,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_ till 0x_
>
> All the address below 0xC000_(ie 3G from 0x0 to 0xBFFF_) 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
>
> ___
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: relocatable modules' symbols
Hi Horseriver,
On Sun, Feb 24, 2013 at 7:26 AM, horseriver wrote:
> On Sun, Feb 24, 2013 at 04:00:37PM +0700, Mulyadi Santosa wrote:
>> On Sat, Feb 23, 2013 at 6:45 AM, horseriver 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 0xc010. I know the 0x10 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
>> 0xc00 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
> {
> . = 0xC000 + 0x10;
> /* read-only */
> _text = .;/* Text and read-only data */
>
>
> why use 0xC000 as its start ? why not just use 0x10 only ?
> if use 0xC000,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_ till 0x_
All the address below 0xC000_(ie 3G from 0x0 to 0xBFFF_) 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
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: relocatable modules' symbols
Hi...
On Sun, Feb 24, 2013 at 8:56 AM, horseriver wrote:
> I have find this answer .
> It is defined in lds script file .
>
> here is the code :
> SECTIONS
> {
> . = 0xC000 + 0x10;
> /* read-only */
> _text = .;/* Text and read-only data */
>
>
> why use 0xC000 as its start ? why not just use 0x10 only ?
> if use 0xC000,every linked symbole will be prefixed by 0xc , what is
> the purpose ?
maybe because some symbols are object of relocation, so their address
don't need to be incremented with 0xc000 .
Different situation with startup_32. AFAIK it's doing many thing
during early protected mode initialization, so its address must be set
to certain number.
--
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
Re: relocatable modules' symbols
On Sun, Feb 24, 2013 at 04:00:37PM +0700, Mulyadi Santosa wrote:
> On Sat, Feb 23, 2013 at 6:45 AM, horseriver 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 0xc010. I know the 0x10 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
> 0xc00 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
{
. = 0xC000 + 0x10;
/* read-only */
_text = .;/* Text and read-only data */
why use 0xC000 as its start ? why not just use 0x10 only ?
if use 0xC000,every linked symbole will be prefixed by 0xc , what is the
purpose ?
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
Re: relocatable modules' symbols
On Sat, Feb 23, 2013 at 6:45 AM, horseriver 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 0xc010. I know the 0x10 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 0xc00 a.k.a a bit above 3 GiB on x86 32 bit machine -- 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
