On Wed, Sep 21, 2022 at 07:15:07AM -0700, Dave Hansen wrote:
In the end, the delay is because of buggy, circa 2006 chipsets? So, we use a CPU vendor specific check to approximate that the chipset is recent and not affected by the bug? If so, is there no better way to check for a newer chipset than this?
So I did some git archeology but that particular addition is in some conglomerate, glued-together patch from 2007 which added the cpuidle tree:
commit 4f86d3a8e297205780cca027e974fd5f81064780 Author: Len Brown len.brown@intel.com Date: Wed Oct 3 18:58:00 2007 -0400
cpuidle: consolidate 2.6.22 cpuidle branch into one patch
so the most precise check here should be to limit that dummy read to that Intel chipset which needed it. Damned if I knew how to figure out which...