1 /* 2 * x86_has_fpu.c 3 * 4 * Test for an x86 FPU, and do any necessary setup. 5 */ 6 7 #if __SIZEOF_POINTER__ == 4 8 #include <i386/x86_init_fpu.c> 9 #elif __SIZEOF_POINTER__ == 8 10 #include <x86_64/x86_init_fpu.c> 11 #else 12 #error "Unable to build for to-be-defined architecture type" 13 #endif 14 #if 0 15 #include <inttypes.h> 16 #include <sys/fpu.h> 17 18 static inline uint64_t get_cr0(void) 19 { 20 #if __SIZEOF_POINTER__ == 4 21 uint32_t v; 22 asm("movl %%cr0,%0":"=r"(v)); 23 #elif __SIZEOF_POINTER__ == 8 24 uint64_t v; 25 asm("movq %%cr0,%0":"=r"(v)); 26 #else 27 #error "Unable to build for to-be-defined architecture type" 28 #endif 29 return v; 30 } 31 32 static inline void set_cr0(uint32_t v) 33 { 34 #if __SIZEOF_POINTER__ == 4 35 asm volatile ("movl %0,%%cr0"::"r" (v)); 36 #elif __SIZEOF_POINTER__ == 8 37 asm volatile ("movq %0,%%cr0"::"r" ((uint64_t)v)); 38 #else 39 #error "Unable to build for to-be-defined architecture type" 40 #endif 41 } 42 43 #define CR0_PE 0x00000001 44 #define CR0_MP 0x00000002 45 #define CR0_EM 0x00000004 46 #define CR0_TS 0x00000008 47 #define CR0_ET 0x00000010 48 #define CR0_NE 0x00000020 49 #define CR0_WP 0x00010000 50 #define CR0_AM 0x00040000 51 #define CR0_NW 0x20000000 52 #define CR0_CD 0x40000000 53 #define CR0_PG 0x80000000 54 55 int x86_init_fpu(void) 56 { 57 uint32_t cr0; 58 uint16_t fsw = 0xffff; 59 uint16_t fcw = 0xffff; 60 61 cr0 = get_cr0(); 62 cr0 &= ~(CR0_EM | CR0_TS); 63 cr0 |= CR0_MP; 64 set_cr0(cr0); 65 66 asm volatile ("fninit"); 67 asm volatile ("fnstsw %0":"+m" (fsw)); 68 if (fsw != 0) 69 return -1; 70 71 asm volatile ("fnstcw %0":"+m" (fcw)); 72 if ((fcw & 0x103f) != 0x3f) 73 return -1; 74 75 /* Techically, this could be a 386 with a 287. We could add a check 76 for that here... */ 77 78 return 0; 79 } 80 #endif 81
