src/lib/libc/aarch64/string/memset_zva64.S, branch main FreeBSD source tree libc/aarch64: Add memset for a 64 byte dc zva 2026-02-03T17:11:51+00:00 Andrew Turner andrew@FreeBSD.org 2026-02-03T14:01:32+00:00 32d1f18865abe94d351a6f178a93b7195595ec69 On arm64 we can use the "dc zva" instruction to zero memory. The CPU tells software if the instruction is implemented, and if so the size and alignment it will use. When the size is 64-bytes the Arm Optimized Routines implementation of memset can use dc zva to zero memory, and has a build flag to skip checking. Use this flag to build a version of memset that will be used when this assumption is true. Sponsored by: Arm Ltd Differential Revision: https://reviews.freebsd.org/D54776 
On arm64 we can use the "dc zva" instruction to zero memory. The CPU
tells software if the instruction is implemented, and if so the size
and alignment it will use.

When the size is 64-bytes the Arm Optimized Routines implementation of
memset can use dc zva to zero memory, and has a build flag to skip
checking.

Use this flag to build a version of memset that will be used when this
assumption is true.

Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D54776