Re: [PATCH] Enable AT_PLATFORM for Loongson 2F CPU

[David Daney <ddaney@xxxxxxxxxxxxxxxxxx>]

On 11/15/2010 03:50 PM, Robert Millan wrote:
> El 11/11/10 15:47:35, en/na Robert Millan va escriure:
> > >  -		__cpu_name[cpu] = "ICT Loongson-2";
> > >  +		switch (c->processor_id&  PRID_REV_MASK) {
> > >  +		case PRID_REV_LOONGSON2E:
> > >  +			__cpu_name[cpu] = "ICT Loongson-2E";
> Actually, the V0.2 / V0.3 that follows in cpuinfo output
> already indicates revision.  And I noticed that appending
> the 'E' or 'F' breaks GCC's -march=native option (which
> works by parsing /proc/cpuinfo).

Good catch, this is true, __cpu_name for better or worse is part of the 
kernel/user ABI.  GCC parses this in gcc/config/mips/driver-native.c


> Please use this patch instead.
>
>
>
> loongson2f.diff
>
>
>
> Signed-off-by: Robert Millan<rmh@xxxxxxx>

Acked-by: David Daney <ddaney@xxxxxxxxxxxxxxxxxx>


> diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
> index fd1d39e..58844f6 100644
> --- a/arch/mips/include/asm/elf.h
> +++ b/arch/mips/include/asm/elf.h
> @@ -344,6 +344,12 @@ extern int dump_task_fpu(struct task_struct *, elf_fpregset_t *);
>   #define ELF_PLATFORM  __elf_platform
>   extern const char *__elf_platform;
>
> +static inline void set_elf_platform(int cpu, const char *plat)
> +{
> +	if (cpu == 0)
> +		__elf_platform = plat;
> +}
> +
>   /*
>    * See comments in asm-alpha/elf.h, this is the same thing
>    * on the MIPS.
> diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
> index 71620e1..accde65 100644
> --- a/arch/mips/kernel/cpu-probe.c
> +++ b/arch/mips/kernel/cpu-probe.c
> @@ -614,6 +614,14 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu)
>   	case PRID_IMP_LOONGSON2:
>   		c->cputype = CPU_LOONGSON2;
>   		__cpu_name[cpu] = "ICT Loongson-2";
> +		switch (c->processor_id&  PRID_REV_MASK) {
> +		case PRID_REV_LOONGSON2E:
> +			set_elf_platform(cpu, "loongson2e");
> +			break;
> +		case PRID_REV_LOONGSON2F:
> +			set_elf_platform(cpu, "loongson2f");
> +			break;
> +		}
>   		c->isa_level = MIPS_CPU_ISA_III;
>   		c->options = R4K_OPTS |
>   			     MIPS_CPU_FPU | MIPS_CPU_LLSC |
> @@ -957,14 +965,12 @@ static inline void cpu_probe_cavium(struct cpuinfo_mips *c, unsigned int cpu)
>   		c->cputype = CPU_CAVIUM_OCTEON_PLUS;
>   		__cpu_name[cpu] = "Cavium Octeon+";
>   platform:
> -		if (cpu == 0)
> -			__elf_platform = "octeon";
> +		set_elf_platform(cpu, "octeon");
>   		break;
>   	case PRID_IMP_CAVIUM_CN63XX:
>   		c->cputype = CPU_CAVIUM_OCTEON2;
>   		__cpu_name[cpu] = "Cavium Octeon II";
> -		if (cpu == 0)
> -			__elf_platform = "octeon2";
> +		set_elf_platform(cpu, "octeon2");
>   		break;
>   	default:
>   		printk(KERN_INFO "Unknown Octeon chip!\n");