Am Montag, den 18.02.2013, 12:21 -0700 schrieb Marc Jones: > On Mon, Feb 18, 2013 at 9:24 AM, Paul Menzel wrote:
> > Am Montag, den 18.02.2013, 17:09 +0100 schrieb Paul Menzel: > > > >> searching for ACPI in the output of `dmesg` I noticed the following > >> message. > >> > >> $ uname -v > >> #1 SMP Debian 3.2.35-2 > >> $ dmesg | grep -i acpi > >> [ 0.154063] ACPI: BIOS offers _BFS > >> [ 0.154067] ACPI: If "acpi.bfs=1" improves resume, please > >> notify [email protected] > >> > >> Doing > >> > >> $ git grep _GTA for correctness, that was supposed to be `git grep _BFS`. > >> reveals that it is only implemented in the DSDT of AMD based boards. > > The kernel sees the ACPI method, but doesn't do anything with it. If > you would like the kernel to use the method, pass acpi.bfs=1. > > > Looking at the actual “implementation” it looks like it is not > > implemented at all (see for AMD Thatcher’s DSDT) [1]. ;-) > ... > >> Was this ever tested by adding `acpi.bfs=1` to the Linux kernel command > >> line and what was the outcome? A test on AMD Persimmon would be very > >> interesting. > > Why would this be interesting? As noted, the method is present, but > doesn't do anything. So why is it there in the first place? > Some debug information could be enabled if the OS called the function. I see. I read the Linux ACPI message »If "acpi.bfs=1" improves resume, …« that way, that resume will be improved (by being quicker). I guess it was supposed to mean, »If your system has less problems with "acpi.bfs=1" than without, please …«. Sorry for the confusion. > >> It looks like support for this has been removed in the meantime though > >> > >> commit 3f6f49c7854c9294119437a82c5b35be78f9cea6 > >> Author: Len Brown <[email protected]> > >> Date: Thu Jul 26 20:08:54 2012 -0400 > >> > >> ACPI: delete _GTS/_BFS support > >> > >> since Linux Git tag v3.6-rc2. > > The function is part of the spec up to 4.0 and Len recommends that it > be remove it in the future revisions. > > It seems safe to remove it, but it isn't causing harm and is part of > the spec as implemented by coreboot. True. Thanks, Paul
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