Location of syscall wrappers

Hi,

If I remember correctly, there used to be syscall wrappers (_syscall3() etc) in the kernel that could be used to make system calls without any library support. I'm not able to locate them for i386. Where are they?

Thanks,

Rajat
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Re: Location of syscall wrappers

On Feb 7, 2008 1:35 AM, Rajat Jain wrote:
>
> Hi,
>
> If I remember correctly, there used to be syscall wrappers (_syscall3() etc) in the kernel that could be used to make system calls
> without any library support. I'm not able to locate them for i386. Where are they?

Use syscall(SYSTEM_CALL_NUMBER, arg1, arg2, arg3);

_syscall3() macro are are not supported nowadays.

http://lkml.org/lkml/2007/7/5/314

Sachin

>
> Thanks,
>
> Rajat
>
> --
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RE: Location of syscall wrappers

Hi,

>
> Use syscall(SYSTEM_CALL_NUMBER, arg1, arg2, arg3);
>
> _syscall3() macro are are not supported nowadays.
>
> http://lkml.org/lkml/2007/7/5/314
>

Who is supposed to provide syscall()?? C library? Where do I find its definition (not declaration)?

What is an application supposed to do if it does not want to use the library?

Thanks,

Rajat
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Re: Location of syscall wrappers

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On Thu, Feb 07, 2008 at 02:12:38PM +0530, Rajat Jain wrote:
> Hi,
>=20
> >=20
> > Use syscall(SYSTEM_CALL_NUMBER, arg1, arg2, arg3);
> >=20
> > _syscall3() macro are are not supported nowadays.
> >=20
> > http://lkml.org/lkml/2007/7/5/314
> >=20
>=20
> Who is supposed to provide syscall()?? C library? Where do I find its
> definition (not declaration)?

libc provides syscall(). Definition can be found in syscall(2).

Use is like this (implementing inotify_add_watch()):

#include
#include
#include

static int inotify_add_watch(int fd, const char *path, unsigned int mask)
{
return syscall(__NR_inotify_add_watch, fd, path, mask);
}


> What is an application supposed to do if it does not want to use the
> library?

The same as an application should do if it wants to use printf() but
not libc: implement it yourself.


Erik

--=20
They're all fools. Don't worry. Darwin may be slow, but he'll
eventually get them. -- Matthew Lammers in alt.sysadmin.recovery

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Re: Location of syscall wrappers

Hi...

On Feb 7, 2008 3:42 PM, Rajat Jain wrote:
> Who is supposed to provide syscall()?? C library? Where do I find its definition (not declaration)?

I think it could be the C kernel headers. I mean something like
/usr/include/asm...

> What is an application supposed to do if it does not want to use the library?

by calling sysenter or int 0x80 and put related parameters in certain registers?

regards,

Mulyadi.
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Re: Location of syscall wrappers

Hi..

On Feb 7, 2008 10:53 PM, Scott Lovenberg wrote:
> for 64 bit:
> /usr/include/asm-x86_64/ioctls.h
> /usr/include/bits/ioctls.h
>
> so, for all machines:
> /usr/include/asm-%arch%/ioctls.h
>

Thank you for the clarification.

regards,

Mulyadi.
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Re: Location of syscall wrappers

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Mulyadi Santosa wrote:
> Hi...
>
> On Feb 7, 2008 3:42 PM, Rajat Jain wrote:
>
>> Who is supposed to provide syscall()?? C library? Where do I find its definition (not declaration)?
>>
>
> I think it could be the C kernel headers. I mean something like
> /usr/include/asm...
>
>
>> What is an application supposed to do if it does not want to use the library?
>>
>
> by calling sysenter or int 0x80 and put related parameters in certain registers?
>
> regards,
>
> Mulyadi.
>
for 64 bit:
/usr/include/asm-x86_64/ioctls.h
/usr/include/bits/ioctls.h

so, for all machines:
/usr/include/asm-%arch%/ioctls.h

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Mulyadi Santosa wrote:
cite="mid:f284c33d0802070740i29ff633bn95963585b69648f9@mail. gmail.com"
type="cite">

Hi...



On Feb 7, 2008 3:42 PM, Rajat Jain  wrote:

  

Who is supposed to provide syscall()?? C library? Where do I find its definition (not declaration)?

    

I think it could be the C kernel headers. I mean something like

/usr/include/asm...



  

What is an application supposed to do if it does not want to use the library?

    

by calling sysenter or int 0x80 and put related parameters in certain registers?



regards,



Mulyadi.