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cpufeatures says AES intrinsics are available on the BCM2711 when they are not #1542
Closed as duplicate
Description
I noticed that aes-0.9.3 crashes executing an aes intrinsic on the RaspberryPi compute module 4, which uses a BCM2711. Apparently, this cpu doesn't have the aes intrinsics even though it is an Armv8. Some sleuthing seems to point to the cpufeatures crate:
# cat /proc/cpuinfo
processor : 0
BogoMIPS : 108.00
Features : fp asimd evtstrm crc32 cpuid
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd08
CPU revision : 3
processor : 1
BogoMIPS : 108.00
Features : fp asimd evtstrm crc32 cpuid
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd08
CPU revision : 3
processor : 2
BogoMIPS : 108.00
Features : fp asimd evtstrm crc32 cpuid
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd08
CPU revision : 3
processor : 3
BogoMIPS : 108.00
Features : fp asimd evtstrm crc32 cpuid
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd08
CPU revision : 3
# /tmp/aes-intrinsics-test
Hardware AES *is* available
# ./mod-f1ce64266db6b712 # <--- the aes crate's tests
running 9 tests
Illegal instruction (core dumped)
Activity
der-winter-justus commentedon Sep 16, 2026
Some more digging revealed the culprit to be
RUSTFLAGS="-C target-cpu=cortex-a72"which seems to override the runtime check. Adding-C target-feature=-aeshelps, but this is not obvious.newpavlov commentedon Sep 16, 2026
Yeah, it's a toolchain issue (see the duplicate link).
-C target_cpu=cortex-a72(and-target-cpu=nativeon Raspberry Pi) wrongly enables crypto features that are optional on Cortex-A72 rust-lang/rust#125033