On 22-09-2022 01:21 am, Borislav Petkov wrote: > 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@xxxxxxxxx> > Date: Wed Oct 3 18:58:00 2007 -0400 > > cpuidle: consolidate 2.6.22 cpuidle branch into one patch In fact, the code has moved around a fair bit and the check in its initial form goes as far back as ACPI's posting for inclusion in the kernel in March 2002 [1]. We could not find any way of digging further back, yet. Prior to that, I think the ACPI enablement code was being released independent of the kernel per https://kernel.org/doc/ols/2004/ols2004v1-pages-121-132.pdf and was included in Andrew's mm tree for a while. >From https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git the first tag that contains code with the dummy read is v2.5.7 AFAICS. Ananth [1] https://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux-fullhistory.git/commit/?id=972c16130d9dc182cedcdd408408d9eacc7d6a2d
