I think this is fine. It's been a very long time since we had to worry
about this.
Keith
On Mon, 2010-08-16 at 01:17 -0700, Vinson Lee wrote:
> I am proposing to remove the check_os_katmai_support function from
> u_cpu_detect.
>
> util: Remove check_os_katmai_support.
>
> check_os_katmai_support checks that the operating system running on a
> SSE-capable processor supports SSE. This is necessary for unpatched 2.2.x and
> earlier kernels. 2.4.x and later kernels support SSE.
>
> check_os_katmai_support will disable SSE capabilities for 32-bit x86
> operating systems for which there is no code path. Currently, this function
> handles Linux, Windows, and several BSDs. Mac OS, Cygwin, and Solaris are
> several operating systems with no code paths.
>
> Rather than add code for the unhandled operating systems, remove this
> function altogether. This will fix SSE detection on all recent 32-bit x86
> operating systems. This completely breaks functionality on unpatched 2.2.x
> and earlier kernels, although there are likely no Gallium3D users on such
> operating systems.
>
>
> diff --git a/src/gallium/auxiliary/util/u_cpu_detect.c
> b/src/gallium/auxiliary/util/u_cpu_detect.c
> index 5056351..b9b9f92 100644
> --- a/src/gallium/auxiliary/util/u_cpu_detect.c
> +++ b/src/gallium/auxiliary/util/u_cpu_detect.c
> @@ -194,123 +194,8 @@ check_os_altivec_support(void)
> }
> #endif /* PIPE_ARCH_PPC */
>
> -/* If we're running on a processor that can do SSE, let's see if we
> - * are allowed to or not. This will catch 2.4.0 or later kernels that
> - * haven't been configured for a Pentium III but are running on one,
> - * and RedHat patched 2.2 kernels that have broken exception handling
> - * support for user space apps that do SSE.
> - */
> -#if defined(PIPE_ARCH_X86) || defined (PIPE_ARCH_X86_64)
> -static void
> -check_os_katmai_support(void)
> -{
> -#if defined(PIPE_ARCH_X86)
> -#if defined(PIPE_OS_FREEBSD)
> - int has_sse=0, ret;
> - int len = sizeof (has_sse);
> -
> - ret = sysctlbyname("hw.instruction_sse", &has_sse, &len, NULL, 0);
> - if (ret || !has_sse)
> - util_cpu_caps.has_sse=0;
> -
> -#elif defined(PIPE_OS_NETBSD) || defined(PIPE_OS_OPENBSD)
> - int has_sse, has_sse2, ret, mib[2];
> - int varlen;
> -
> - mib[0] = CTL_MACHDEP;
> - mib[1] = CPU_SSE;
> - varlen = sizeof (has_sse);
> -
> - ret = sysctl(mib, 2, &has_sse, &varlen, NULL, 0);
> - if (ret < 0 || !has_sse) {
> - util_cpu_caps.has_sse = 0;
> - } else {
> - util_cpu_caps.has_sse = 1;
> - }
> -
> - mib[1] = CPU_SSE2;
> - varlen = sizeof (has_sse2);
> - ret = sysctl(mib, 2, &has_sse2, &varlen, NULL, 0);
> - if (ret < 0 || !has_sse2) {
> - util_cpu_caps.has_sse2 = 0;
> - } else {
> - util_cpu_caps.has_sse2 = 1;
> - }
> - util_cpu_caps.has_sse = 0; /* FIXME ?!?!? */
> -
> -
> -#elif defined(PIPE_OS_WINDOWS)
> - LPTOP_LEVEL_EXCEPTION_FILTER exc_fil;
> - if (util_cpu_caps.has_sse) {
> - exc_fil = SetUnhandledExceptionFilter(win32_sig_handler_sse);
> -#if defined(PIPE_CC_GCC)
> - __asm __volatile ("xorps %xmm0, %xmm0");
> -#elif defined(PIPE_CC_MSVC)
> - __asm {
> - xorps xmm0, xmm0 /* executing SSE instruction */
> - }
> -#else
> -#error Unsupported compiler
> -#endif
> - SetUnhandledExceptionFilter(exc_fil);
> - }
> -#elif defined(PIPE_OS_LINUX)
> - struct sigaction saved_sigill;
> - struct sigaction saved_sigfpe;
> -
> - /* Save the original signal handlers.
> - */
> - sigaction(SIGILL, NULL, &saved_sigill);
> - sigaction(SIGFPE, NULL, &saved_sigfpe);
> -
> - signal(SIGILL, (void (*)(int))sigill_handler_sse);
> - signal(SIGFPE, (void (*)(int))sigfpe_handler_sse);
> -
> - /* Emulate test for OSFXSR in CR4. The OS will set this bit if it
> - * supports the extended FPU save and restore required for SSE. If
> - * we execute an SSE instruction on a PIII and get a SIGILL, the OS
> - * doesn't support Streaming SIMD Exceptions, even if the processor
> - * does.
> - */
> - if (util_cpu_caps.has_sse) {
> - __asm __volatile ("xorps %xmm1, %xmm0");
> - }
> -
> - /* Emulate test for OSXMMEXCPT in CR4. The OS will set this bit if
> - * it supports unmasked SIMD FPU exceptions. If we unmask the
> - * exceptions, do a SIMD divide-by-zero and get a SIGILL, the OS
> - * doesn't support unmasked SIMD FPU exceptions. If we get a SIGFPE
> - * as expected, we're okay but we need to clean up after it.
> - *
> - * Are we being too stringent in our requirement that the OS support
> - * unmasked exceptions? Certain RedHat 2.2 kernels enable SSE by
> - * setting CR4.OSFXSR but don't support unmasked exceptions. Win98
> - * doesn't even support them. We at least know the user-space SSE
> - * support is good in kernels that do support unmasked exceptions,
> - * and therefore to be safe I'm going to leave this test in here.
> - */
> - if (util_cpu_caps.has_sse) {
> - /* test_os_katmai_exception_support(); */
> - }
> -
> - /* Restore the original signal handlers.
> - */
> - sigaction(SIGILL, &saved_sigill, NULL);
> - sigaction(SIGFPE, &saved_sigfpe, NULL);
> -
> -#else
> - /* We can't use POSIX signal handling to test the availability of
> - * SSE, so we disable it by default.
> - */
> - util_cpu_caps.has_sse = 0;
> -#endif /* __linux__ */
> -#endif
> -
> -#if defined(PIPE_ARCH_X86_64)
> - util_cpu_caps.has_sse = 1;
> -#endif
> -}
> -
>
> +#if defined(PIPE_ARCH_X86) || defined (PIPE_ARCH_X86_64)
> static int has_cpuid(void)
> {
> #if defined(PIPE_ARCH_X86)
> @@ -469,9 +354,6 @@ util_cpu_detect(void)
> util_cpu_caps.cacheline = regs2[2] & 0xFF;
> }
>
> - if (util_cpu_caps.has_sse)
> - check_os_katmai_support();
> -
> if (!util_cpu_caps.has_sse) {
> util_cpu_caps.has_sse2 = 0;
> util_cpu_caps.has_sse3 = 0;
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