On Thursday 01 September 2011, Andrew Stubbs wrote:
Hi all,
I'm currently trying to get GCC to auto-detect what CPU to optimize for by finding out what CPU it's actually running on (the user would only have to pass -mcpu=native). It does this simply by reading /proc/cpuinfo.
The problem is finding what magic numbers correspond to what CPU. I've found the numbers for A8 and A9 empirically, but I'd like a longer list than that!
Does anybody have a list of such numbers?
Or else, perhaps people could just post any number they happen to know?
I do have a few devices other than A8 and A9 lying around I can look at, but the problem there is I don't actually know for certain what exact CPU model those numbers map to, so confirmed numbers only please.
This is what we use in the kernel: to find out the architecture level:
#define CPU_ARCH_UNKNOWN 0 #define CPU_ARCH_ARMv3 1 #define CPU_ARCH_ARMv4 2 #define CPU_ARCH_ARMv4T 3 #define CPU_ARCH_ARMv5 4 #define CPU_ARCH_ARMv5T 5 #define CPU_ARCH_ARMv5TE 6 #define CPU_ARCH_ARMv5TEJ 7 #define CPU_ARCH_ARMv6 8 #define CPU_ARCH_ARMv7 9
int cpu_architecture(void) { int cpu_arch;
if ((read_cpuid_id() & 0x0008f000) == 0) { cpu_arch = CPU_ARCH_UNKNOWN; } else if ((read_cpuid_id() & 0x0008f000) == 0x00007000) { cpu_arch = (read_cpuid_id() & (1 << 23)) ? CPU_ARCH_ARMv4T : CPU_ARCH_ARMv3; } else if ((read_cpuid_id() & 0x00080000) == 0x00000000) { cpu_arch = (read_cpuid_id() >> 16) & 7; if (cpu_arch) cpu_arch += CPU_ARCH_ARMv3; } else if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) { unsigned int mmfr0;
/* Revised CPUID format. Read the Memory Model Feature * Register 0 and check for VMSAv7 or PMSAv7 */ asm("mrc p15, 0, %0, c0, c1, 4" : "=r" (mmfr0)); if ((mmfr0 & 0x0000000f) >= 0x00000003 || (mmfr0 & 0x000000f0) >= 0x00000030) cpu_arch = CPU_ARCH_ARMv7; else if ((mmfr0 & 0x0000000f) == 0x00000002 || (mmfr0 & 0x000000f0) == 0x00000020) cpu_arch = CPU_ARCH_ARMv6; else cpu_arch = CPU_ARCH_UNKNOWN; } else cpu_arch = CPU_ARCH_UNKNOWN;
return cpu_arch; }
[ within the /proc/cpuinfo code: ] ... seq_printf(m, "\nCPU implementer\t: 0x%02x\n", read_cpuid_id() >> 24); seq_printf(m, "CPU architecture: %s\n", proc_arch[cpu_architecture()]);
if ((read_cpuid_id() & 0x0008f000) == 0x00000000) { /* pre-ARM7 */ seq_printf(m, "CPU part\t: %07x\n", read_cpuid_id() >> 4); } else { if ((read_cpuid_id() & 0x0008f000) == 0x00007000) { /* ARM7 */ seq_printf(m, "CPU variant\t: 0x%02x\n", (read_cpuid_id() >> 16) & 127); } else { /* post-ARM7 */ seq_printf(m, "CPU variant\t: 0x%x\n", (read_cpuid_id() >> 20) & 15); } seq_printf(m, "CPU part\t: 0x%03x\n", (read_cpuid_id() >> 4) & 0xfff); } seq_printf(m, "CPU revision\t: %d\n", read_cpuid_id() & 15); ...
Arnd