On Wed, Sep 8, 2021, 11:47 AM Colin Percival <cperc...@freebsd.org> wrote:
> On 9/8/21 9:01 AM, John Baldwin wrote: > > On 9/7/21 6:32 PM, Colin Percival wrote: > >> Disable acpi_timer_test by default > >> This disables testing the ACPI timer by default, forcing the > use of > >> ACPI-fast rather than ACPI-safe. The broken-ACPI-timers workaround > >> can be re-enabled by setting the hw.acpi.timer_test_enabled=1 > tunable. > >> This speeds up the FreeBSD boot process by 140 ms on an EC2 > c5.xlarge > >> instance. > >> This change will not be MFCed. > >> Assuming no problems are reported, acpi_timer_test, the > associated > >> tunable, and the ACPI-safe timecounter should be removed in > FreeBSD 15. > >> Relnotes: The ACPI-safe timer is disabled in favour of > >> ACPI-fast; > >> if timekeeping issues are observed, please test > with > >> hw.acpi.timer_test_enabled=1 in loader.conf and > report > >> if that fixes the problem. > > > > Perhaps it should default to '1' for i386 and '0' otherwise? The > relevant > > chipsets were 32-bit only, so this would be a simple way to skip the > test for > > modern hardware, and you could probably MFC that safely. > > That option was discussed, but I decided that it was probably safer to > keep it enabled by default in 13 in case the test was detecting systems > which are broken in other ways. > > Googling for "ACPI-safe" (which shows up if the test fails) finds forum > discussions from the mid-2010s, but it's not clear whether that's due to > very old hardware, new ACPI timer issues, or other timekeeping problems > -- I figured it was best to play it safe for something which would be > going into a stable branch though. > I think John's suggestion is a good balance. It will also tell us if there is a need on amd64. Having it tagged as i386 also will highlight it better should the time come to remove it later. Warner -- > Colin Percival > Security Officer Emeritus, FreeBSD | The power to serve > Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid > _______________________________________________ dev-commits-src-main@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/dev-commits-src-main To unsubscribe, send any mail to "dev-commits-src-main-unsubscr...@freebsd.org"
