Re: [uml-devel] skas3 patch breaks ATI video drivers

[Blaisorblade <blaisorblade@yahoo.it>]

On Tuesday 25 January 2005 11:55, Marcus Better wrote:
> Blaisorblade wrote:
> > *strange* that a kernel module uses the "_syscall" macro to do a syscall
> > with "int 0x80" while already being in kernelspace...
>
> It's interesting that the module contains the following code:
>
> ------------------------
> //#define FGL_USE_SCT /* for developer use only */
>
> //...<snip>...
>
>
> #ifdef FGL_USE_SCT
> // get direct function pointers from sys_call_table for calling
> #else /* FGL_USE_SCT */
> // call functions indirectly by using the syscall macros,
> // entrypoints get defined by below constructs
>
> #if !defined(__ia64__)
> // the macros do use errno variable
> static int errno;
> #endif // __ia64__
>
> // int mlock(const void *addr, size_t len);
> _syscall2(int, mlock, const void *, addr, size_t, len )
> // int munlock(const void *addr, size_t len);
> _syscall2(int, munlock, const void *, addr, size_t, len )
> #if !defined(__ia64__)
> #if !defined(__x86_64__)
> // TODO: ia64
> // int modify_ldt(int func, void *ptr, unsigned long bytecount);
> _syscall3( int, modify_ldt, int, func, void *, ptr, unsigned long,
> bytecount )
> #endif
> #endif
> #endif /* FGL_USE_SCT */
> --------------------------

> I actually tried to #define FGL_USE_SCT, but it didn't compile either.
Ok, now I get it... they're trying to workaround the fact that modify_ldt() is 
not exported.

Thus they are probably violating the GPL (well, let's not start anything on 
this), because the syscall table has been unexported on purpose... however 
such tricks will break. I'll add the workaround in next revision, thanks (and 
if I forget, just mail me after the release).
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade


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