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add isb after cpacr update

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Simon Renblad 2025-01-06 11:17:13 +08:00
parent 12cb5c0651
commit 38852ef7c7
1 changed files with 3 additions and 1 deletions
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libcortex_a9/src/fpu.rs
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@ -1,12 +1,14 @@
use core::arch::asm; use core::arch::asm;
/// Enable FPU in the current core. /// Enable FPU in the current core.
/// You must execute an ISB immediately after an update of the CPACR.
/// https://developer.arm.com/documentation/ddi0388/i/system-control/register-descriptions/coprocessor-access-control-register
pub fn enable_fpu() { pub fn enable_fpu() {
unsafe { unsafe {
asm!(" asm!("
mrc p15, 0, r1, c1, c0, 2 mrc p15, 0, r1, c1, c0, 2
orr r1, r1, (0b1111<<20) orr r1, r1, (0b1111<<20)
mcr p15, 0, r1, c1, c0, 2 mcr p15, 0, r1, c1, c0, 2
isb
vmrs r1, fpexc vmrs r1, fpexc
orr r1, r1, (1<<30) orr r1, r1, (1<<30)
vmsr fpexc, r1 vmsr fpexc, r1