Patrick,

There are two methods to disable this remark:

1)      Disable all remarks via the –VR option

2)      Disable the specific remark via the –VW option.

Please see the examples below.

BTW, remarks from iASL are simply suggestions, they are not nearly as serious as warnings or errors. That is why we provide an option to disable all remarks. Remarks do not affect the AML code that is emitted.



    OperationRegion (OPR1, SystemMemory, 0x200, 0x400)
    Field (OPR1, ByteAcc, Lock, Preserve)
    {
        FIE1, 8,
        FIE2, 8,
        Offset(2),
        FIE3, 8
    }


iasl dsdt.asl

Intel ACPI Component Architecture
ASL+ Optimizing Compiler/Disassembler version 20190215
Copyright (c) 2000 - 2019 Intel Corporation

dsdt.asl     15:         Offset(2),
Remark   2158 -                ^ Unnecessary/redundant use of Offset operator

ASL Input:     dsdt.asl - 21 lines, 482 bytes, 2 keywords
AML Output:    dsdt.aml - 72 bytes, 2 named objects, 0 executable opcodes

Compilation complete. 0 Errors, 0 Warnings, 1 Remarks, 1 Optimizations


iasl -vr dsdt.asl    // disable all remarks

Intel ACPI Component Architecture
ASL+ Optimizing Compiler/Disassembler version 20190215
Copyright (c) 2000 - 2019 Intel Corporation

ASL Input:     dsdt.asl - 21 lines, 482 bytes, 2 keywords
AML Output:    dsdt.aml - 72 bytes, 2 named objects, 0 executable opcodes

Compilation complete. 0 Errors, 0 Warnings, 1 Remarks, 1 Optimizations


iasl -vw 2158 dsdt.asl   // disable remark #2158

Intel ACPI Component Architecture
ASL+ Optimizing Compiler/Disassembler version 20190215
Copyright (c) 2000 - 2019 Intel Corporation

ASL Input:     dsdt.asl - 21 lines, 482 bytes, 2 keywords
AML Output:    dsdt.aml - 72 bytes, 2 named objects, 0 executable opcodes

Compilation complete. 0 Errors, 0 Warnings, 0 Remarks, 1 Optimizations


From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Patrick Georgi
Sent: Wednesday, April 3, 2019 12:14 AM
To: devel(a)acpica.org
Subject: [Devel] Field Offset constraints

Hi everybody,

at coreboot[1] we use iasl to compile static ASL for various hardware. Recent versions of iasl emit a notice for redundant Offset statements in Fields, apparently with the expectation that they shouldn't exist.

This poses a problem for us since we're sometimes using Offset as a guard, making sure that we didn't inadvertedly shifted fields around (too much), with the expectation that these were redundant in the "good" case.

Since that operator wasn't really suited for that purpose anyway, and now throws warnings (which we try to avoid in our builds), are there plans to add some keyword for compile time constraints checks, or any objections to having such a feature (should one of us decide to implement it)?

Maybe something like

Field (NAME, ByteAcc, Lock, Preserve)
{
    Item(FIE1, 0, 0, 8)
    Item(FIE2, 1, 0, 8)
    Offset(0x10)
    Item(FIE3, 0x10, 0, 8)
}

in which Item(Name, Byte, Bit, Length) would compile to "Name, Length," inside a field after ensuring that the byte and bit offsets match the current location.

Thoughts?

Thanks,
Patrick Georgi

[1] https://www.coreboot.org/
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