Re: [Qemu-devel] [PATCH] ACPI DSDT: Make control method `IQCR` serialized

[Laszlo Ersek <lersek@redhat.com>]

On 11/14/13 13:16, Michael S. Tsirkin wrote:
> Forward-port the following commit from seabios:
> 
> commit 995bbeef78b338370f426bf8d0399038c3fa259c
> Author: Paul Menzel <paulepanter@users.sourceforge.net>
> Date:   Thu Oct 3 11:30:52 2013 +0200
> 
>     The ASL Optimizing Compiler version 20130823-32 [Sep 11 2013] issues the
>     following warning.
> 
>             $ make
>             […]
>               Compiling IASL out/src/fw/acpi-dsdt.hex
>             out/src/fw/acpi-dsdt.dsl.i    360:         Method(IQCR, 1, NotSerialized) {
>             Remark   2120 -                                     ^ Control Method should be made Serialized (due to creation of named objects within)
>             […]
>             ASL Input:     out/src/fw/acpi-dsdt.dsl.i - 475 lines, 19181 bytes, 316 keywords
>             AML Output:    out/src/fw/acpi-dsdt.aml - 4407 bytes, 159 named objects, 157 executable opcodes
>             Listing File:  out/src/fw/acpi-dsdt.lst - 143715 bytes
>             Hex Dump:      out/src/fw/acpi-dsdt.hex - 41661 bytes
> 
>             Compilation complete. 0 Errors, 0 Warnings, 1 Remarks, 246 Optimizations
>             […]
> 
>     After changing the parameter from `NotSerialized` to `Serialized`, the
>     remark is indeed gone and there is no size change.
> 
>     The remark was added in ACPICA version 20130517 [1] and gives the
>     following explanation.
> 
>             If a thread blocks within the method for any reason, and another thread
>             enters the method, the method will fail because an attempt will be
>             made to create the same (named) object twice.
> 
>             In this case, issue a remark that the method should be marked
>             serialized. ACPICA BZ 909.
> 
>     [1] https://github.com/acpica/acpica/commit/ba84d0fc18ba910a47a3f71c68a43543c06e6831
> 
>     Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
> 
> Reported-by: Marcel Apfelbaum <marcel.a@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/i386/acpi-dsdt.dsl               | 2 +-
>  hw/i386/acpi-dsdt.hex.generated     | 4 ++--
>  hw/i386/q35-acpi-dsdt.dsl           | 2 +-
>  hw/i386/q35-acpi-dsdt.hex.generated | 4 ++--
>  4 files changed, 6 insertions(+), 6 deletions(-)

The analysis / evolution of the iasl change
<https://bugs.acpica.org/show_bug.cgi?id=909> is instrumental.

The patch looks good to me (although you could sell me anything in the
binary part).

Reviewed-by: Laszlo Ersek <lersek@redhat.com>