On Sat, Nov 16, 2019 at 9:06 PM Dan Williams [off-list ref] wrote:

On Wed, Nov 13, 2019 at 11:17 PM Yunfeng Ye [off-list ref] wrote:

quoted

The commit 0f27cff8597d ("ACPI: sysfs: Make ACPI GPE mask kernel
parameter cover all GPEs") says:
  "Use a bitmap of size 0xFF instead of a u64 for the GPE mask so 256
   GPEs can be masked"

But the masking of GPE 0xFF it not supported and the check condition
"gpe > ACPI_MASKABLE_GPE_MAX" is not valid because the type of gpe is
u8.

So modify the macro ACPI_MASKABLE_GPE_MAX to 0x100, and drop the "gpe >
ACPI_MASKABLE_GPE_MAX" check. In addition, update the docs "Format" for
acpi_mask_gpe parameter.

Fixes: 0f27cff8597d ("ACPI: sysfs: Make ACPI GPE mask kernel parameter cover all GPEs")
Signed-off-by: Yunfeng Ye <redacted>
---
v1 -> v2:
 - drop the "gpe > ACPI_MASKABLE_GPE_MAX" check
 - update the docs "Format" from <int> to <byte> for acpi_mask_gpe parameter
 - update the commit comment

 Documentation/admin-guide/kernel-parameters.txt | 2 +-
 drivers/acpi/sysfs.c                            | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

Bisect flags commit eb09878e1301 "ACPI: sysfs: Change
ACPI_MASKABLE_GPE_MAX to 0x100" in -next as the reason for a boot
regression in my qemu-kvm test environment. It spews:

[    1.456728] ACPI: Masking GPE 0x0.
...
[  161.721420] ACPI: Masking GPE 0x0.

...and then hangs.

A straight revert gets the configuration back on its feet.

qemu-system-x86_64 --version
QEMU emulator version 4.0.50 (v4.0.0-928-g49c6c6ac0cd8)

OK, I'll drop it then, thanks!