problem with <asm/semaphore.h>

problem with <asm/semaphore.h>

[Hossein Mobahi]

Hi

I compiled the following code with gcc under Redhat
7.2 :

#include <asm/semaphore.h>
main()
{
    struct semaphore sum;
}

It doesn't compile, saying "storage size of `sem'
isn't known".
Please guide me how to fix it.

Sincerely

--Hossein Mobahi


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Re: problem with <asm/semaphore.h>

[bonganilinux]

I think you a trying to include a file from the linux source
which will not work for use-space apps. Try using 
#include <semaphore.h> instead 


> Hi
> 
> I compiled the following code with gcc under Redhat
> 7.2 :
> 
> #include <asm/semaphore.h>
> main()
> {
>     struct semaphore sum;
> }
> 
> It doesn't compile, saying "storage size of `sem'
> isn't known".
> Please guide me how to fix it.
> 
> Sincerely
> 
> --Hossein Mobahi
> 
> 
> __________________________________________________
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> Yahoo! - Official partner of 2002 FIFA World Cup
> http://fifaworldcup.yahoo.com
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Re: problem with <asm/semaphore.h>

[Shanks]

Hi Hossein,

If you look inside <asm/semaphore.h> you will see that
the definition of struct semaphore is within a 
conditional #ifdef __KERNEL__

Hence __KERNEL__ needs to be defined for this code to
compile.
Try compiling like this
$> gcc -D__KERNEL__ file.c

Regards,
Shanks

--- Hossein Mobahi <hmobahi@yahoo.com> wrote:
> Hi
> I compiled the following code with gcc under Redhat
> 7.2 :
> #include <asm/semaphore.h>
> main()
> {
>     struct semaphore sum;
> }
> 
> It doesn't compile, saying "storage size of `sem'
> isn't known".
> 
> Sincerely
> --Hossein Mobahi

__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com

Re: problem with <asm/semaphore.h>

[Thomas 'Dent' Mirlacher]

On Tue, 4 Jun 2002 bonganilinux@mweb.co.za wrote:

> I think you a trying to include a file from the linux source
> which will not work for use-space apps. Try using 
> #include <semaphore.h> instead 

yes, sounds right, since struct semaphore in asm/semaphore will be
defined only if __KERNEL__ is defined.

	tm

-- 
in some way i do, and in some way i don't.

Re: problem with <asm/semaphore.h>

[Robert Hancock]

liangbowen wrote:
> Hi
> 
> I compiled the following code with gcc under FC2 :
> 
> #include <asm/semaphore.h>
> main()
> {
>     struct semaphore sum;
> 
> }
> 
> It doesn't compile, saying "storage size of `sem'
> isn't known".
> 
> and I looked inside asm/semaphore.h, I saw:
> #ifndef I386_SEMAPHORE_H
> #define I386_SEMAPHORE_H
> 
> #include <linux/linkage.h>
> 
> #endif
> 
> Did I missed something? Please guide me how to fix it.
> 
> Sincerely

You're trying to use a kernel data structure in a user-space program. 
Don't. The definitions in that header are inside #ifdef __KERNEL__ and 
so the provided userspace headers remove that part.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

Re: problem with <asm/semaphore.h>

[Robert Hancock]

liangbowen wrote:
>> You're trying to use a kernel data structure in a user-space program.
>> Don't. The definitions in that header are inside #ifdef __KERNEL__ and
>> so the provided userspace headers remove that part.
> 
> someone've said the exact same thing, and he said that I can add the -
> D__KERNEL__ to the compilation options,
> but I can't see any #ifdef __KERNEL__ macro in that header(<asm/
> semaphore.h>).
> Is my header differ from yours?
> 

It's because the userspace headers have been processed with unifdef to 
remove any sections which are inside #ifdef __KERNEL__, since userspace 
apps are not supposed to see those sections.

I'm not sure why you want to use a semaphore in a userspace program. 
Even if you can get it to compile, they definitely won't function 
properly. Aside from the legal issues (using internal kernel code like 
that would make your program a derived work of the kernel and thus 
covered under the GPL).

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

Re: problem with <asm/semaphore.h>

[Robert Hancock]

liangbowen wrote:
> maybe you've misunderstood my meaning.  I mean the whole <asm/
> semaphore.h> header file has only  4 lines of code in total:
> #ifndef I386_SEMAPHORE_H
> #define I386_SEMAPHORE_H
> #include <linux/linkage.h>
> #endif
> 
> it's supposed to have more codes than that. like
> struct semaphore {
> 	int count;
> 	int waking;
> 	int lock ;			/* to make waking testing atomic */
> 	struct wait_queue * wait;
> };
> and the down(), up() functions.
> 
> but I can't see any of those codes, not even the #ifdef __KERNEL__
> macro.
> 

It does in the kernel version of that header. The userspace version of 
that header has everything inside #ifdef __KERNEL__ stripped out.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/