Re: [Mesa3d-dev] Re: [Xpert]mesa assuming glibc 2.2? (Cannot compile 4.1 on RedHat 6.2)

[Brian P. <br...@va...>]

"Marcelo E. Magallon" wrote:
> 
> >> Brian Paul <br...@va...> writes:
> 
>  > If anyone knows a solution to this I'd like to hear it.
> 
>  Sometime ago I submitted a patch for this (#403332).  The comment
>  reads:
> 
>  | If the use of KATMAI instructions is enabled, on linux it's necessary
>  | to have recent kernel headers installed (these are coupled to the C
>  | library, so suggesting to place/change a link in /usr/src/ is not
>  | advisable). There are two options for it's detection at compile time,
>  | one is using LINUX_KERNEL_VERSION, what this patch does, the other is
>  | checking for X86_FXSR_MAGIC to be defined. I'm sure Gareth can make a
>  | recommendation as to which is better. With either of them, I think
>  | it's important to provide the user with an error that at least
>  | suggests a course of action (the current one goes along the lines of
>  | "magic is not a member of structure sigcontext", IIRC)
> 
>  | The patch uses 2.4.0 as a reference point, I'm not really sure when
>  | the SSE support was introduced in the kernel, but it's not on the
>  | 2.2.18 I looked at.
> 
>  The patch, which is not on SF (weird) is basically:
> 
> Index: extras/Mesa/src/X86/common_x86.c
> ===================================================================
> RCS file: /cvsroot/dri/xc/xc/extras/Mesa/src/X86/common_x86.c,v
> retrieving revision 1.10
> diff -u -r1.10 common_x86.c
> --- extras/Mesa/src/X86/common_x86.c    2001/02/12 20:42:42     1.10
> +++ extras/Mesa/src/X86/common_x86.c    2001/06/05 15:22:50
> @@ -88,6 +88,11 @@
>  extern void gl_test_os_katmai_exception_support( void );
> 
>  #if defined(__linux__) && defined(_POSIX_SOURCE)
> +#include <linux/version.h>
> +#if LINUX_VERSION_CODE < KERNEL_VERSION(2,4,0)
> +#error "linux headers older than 2.4.0 don't provide support for SSE."
> +#endif
> +
>  static void sigill_handler( int signal, struct sigcontext sc )
>  {
>     message( "SIGILL, " );
> 
>  Granted, it's not the best solution, but it's at least an useful error.
>  Some conditionals on the configuration files would do it, too.
>  (HAVE_LINUX_2_4_HEADERS, Imakefile style).  The point is, you need 2.4
>  kernel headers to compile this.


I'd like to see a solution that doesn't interupt compilation.  That
is, if we can't use SSE at compile time, it should just be disabled,
perhaps with a warning.

The trick is there was a patch to Linux 2.2.x that added SSE so just
testing for kernel >= 2.4.0 isn't enough.  Does the presense of
X86_FXSR_MAGIC ensure that the _fpstate.magic field exists?

-Brian