Re: Lenovo ThinkPads need acpi_osi="Linux"

Henrique de Moraes Holschuh
2008-01-13T23:41:34Z

On Sun, 13 Jan 2008, Pavel Machek wrote:
> > The reason it shoudl be turned off is that backlight enabling
> > backlight from a native graphics driver is much faster than running
> > through the video BIOS POST. So if we keep the OSI(Linux)
> > video BIOS POST workaround in place permanently, it would
> > put Linux at a permanent performance disadvantage to Windows.
>
> Hmm, they should not need to do anything.
>
> When linux calls video BIOS with lcall (acpi_sleep=s3_bios), they
> should turn on backlight and put video into text mode. They should
> also make sure mode setting works after that.

IMHO, in that case, we should probably be whitelist-enabling that on
thinkpads (and allow for acpi_sleep=none to override it), or letting
userspace change it at runtime.

> I don't see how ACPI fits into this picture, and I think it can work
> well without ACPI tricks.

It fits because Lenovo did it in ACPI (or used to do it in ACPI, whatever).
We can ask them to not do it, I suppose. But without some sort of
autodetection on our part, I doubt they will remove it.