This is a collection of Intel®’ IA32® Software Developer's Manuals (URL of the day) and AMD' AMD64 Architecture Programmer's Manual together with the related specifications, application notes, white papers, and change logs. The collection aims to keep all available revisions. It was originally created by Michal Necasek, see OS/2 Museum.

If you have a public document, related to the IA32® specifications and missing from the collection, please mail it to me. The content of this URL and all sub-ULRs is available for convenient bulk download by rsync x86docs password "" (empty).

BPIALL

BPIALL, Branch Predictor Invalidate All

The BPIALL characteristics are:

Purpose

Invalidate all entries from branch predictors.

Configuration

This instruction is present only when FEAT_AA32EL1 is implemented. Otherwise, direct accesses to BPIALL are UNDEFINED.

In an implementation where the branch predictors are architecturally invisible, this instruction can execute as a NOP.

Attributes

BPIALL is a 32-bit System instruction.

Field descriptions

This instruction has no applicable fields.

The value in the register specified by <Rt> is ignored.

Executing BPIALL

The PE ignores the value of <Rt>. Software does not have to write a value to this register before issuing this instruction.

When HCR.FB is 1, at Non-secure EL1 this instruction executes as a BPIALLIS.

Accesses to this instruction use the following encodings in the System instruction encoding space:

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b01110b01010b110

if !IsFeatureImplemented(FEAT_AA32EL1) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T7 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T7 == '1' then AArch32_TakeHypTrapException(0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HCR().FB == '1' then BPIALLIS(); else BPIALL(); end; elsif PSTATE.EL == EL2 then BPIALL(); elsif PSTATE.EL == EL3 then BPIALL(); end;


2026-03-12 12:23:09, 2025-09_rel_asl1

Copyright © 2010-2025 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.