ARM: vfp: add VFPv4 capability detection and populate elf_hwcap (18b9dc13) · Commits · 戴 / test

The presence of VFPv4 cannot be detected simply by looking at the FPSID subarchitecture field, as a value >= 2 signifies the architecture as VFPv3 or later. This patch reads from MVFR1 to check whether or not the fused multiply accumulate instructions are supported. Since these are introduced with VFPv4, this tells us what we need to know. Signed-off-by:

Will Deacon <will.deacon@arm.com>

arch/arm/vfp/vfpmodule.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -582,7 +582,6 @@ static int __init vfp_init(void)
		elf_hwcap \|= HWCAP_VFPv3D16;
		}
		#endif
		#ifdef CONFIG_NEON
		/*
		* Check for the presence of the Advanced SIMD
		* load/store instructions, integer and single
		@@ -590,10 +589,13 @@ static int __init vfp_init(void)
		* for NEON if the hardware has the MVFR registers.
		*/
		if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) {
		#ifdef CONFIG_NEON
		if ((fmrx(MVFR1) & 0x000fff00) == 0x00011100)
		elf_hwcap \|= HWCAP_NEON;
		}
		#endif
		if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000)
		elf_hwcap \|= HWCAP_VFPv4;
		}
		}
		return 0;
		}

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