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 getaru...@gmail.com wrote:
Hi Horseriver,
On Sun, Feb 24, 2013 at 7:26 AM, horseriver horseriv...@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 horseriv...@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 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
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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 gprabhun...@gmail.com:
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 getaru...@gmail.com wrote:
Hi Horseriver,
On Sun, Feb 24, 2013 at 7:26 AM, horseriver horseriv...@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 horseriv...@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 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
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Re: relocatable modules' symbols
Hi Horseriver,
On Sun, Feb 24, 2013 at 7:26 AM, horseriver horseriv...@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 horseriv...@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 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
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Re: relocatable modules' symbols
Hi...
On Sun, Feb 24, 2013 at 8:56 AM, horseriver horseriv...@gmail.com 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
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Re: relocatable modules' symbols
On Sat, Feb 23, 2013 at 6:45 AM, horseriver horseriv...@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 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
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 horseriv...@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 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
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relocatable modules' symbols
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? thanks! ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
