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Smith" , Andrew Cooper , Jan Beulich , Julien Grall , Stefano Stabellini Subject: Re: [PATCH v7 1/2] x86/time: introduce command line option to select wallclock Message-ID: References: <20240913075907.34460-1-roger.pau@citrix.com> <20240913075907.34460-2-roger.pau@citrix.com> <49a2404f-0c45-4397-9094-a4189131832f@gmail.com> <78e09ccb-65b7-4022-b9fc-7874e34c1a99@gmail.com> <9288f0de-945f-4056-9934-16b2b1704fb1@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9288f0de-945f-4056-9934-16b2b1704fb1@gmail.com> On Tue, Jan 14, 2025 at 12:44:39PM +0100, Oleksii Kurochko wrote: > > On 1/14/25 12:40 PM, Oleksii Kurochko wrote: > > > > > > On 1/14/25 12:27 PM, Roger Pau Monné wrote: > > > On Tue, Jan 14, 2025 at 12:12:03PM +0100, Oleksii Kurochko wrote: > > > > On 1/13/25 6:52 PM, Roger Pau Monné wrote: > > > > > On Mon, Jan 13, 2025 at 05:07:55PM +0100, Marek Marczykowski-Górecki wrote: > > > > > > On Fri, Sep 13, 2024 at 09:59:06AM +0200, Roger Pau Monne wrote: > > > > > > > Allow setting the used wallclock from the command line. When the option is set > > > > > > > to a value different than `auto` the probing is bypassed and the selected > > > > > > > implementation is used (as long as it's available). > > > > > > > > > > > > > > The `xen` and `efi` options require being booted as a Xen guest (with Xen guest > > > > > > > supported built-in) or from UEFI firmware respectively. > > > > > > > > > > > > > > Signed-off-by: Roger Pau Monné > > > > > > Reviewed-by: Marek Marczykowski-Górecki > > > > > Thanks for the review. > > > > > > > > > > Oleksii, can I get your opinion as Release Manager about whether this > > > > > (and the following patch) would be suitable for committing to staging > > > > > given the current release state? > > > > > > > > > > It's a workaround for broken EFI implementations that many downstreams > > > > > carry on their patch queue. > > > > Based on your commit message, I understand this as addressing a bug ( but not very critical > > > > as IIUC downstreams have the similar patch on their side ). Therefore, if it has been properly > > > > reviewed and tested, we should consider including it in the current release. > > > IIRC at least Qubes, XenServer and XCP-ng have a patch that achieves > > > the same behavior as proposed here. > > > > > > > IIUC, setting the wallclock to EFI should align with the behavior Xen had previously. > > > > It might be preferable to use that argument as the default for a while, allowing others to verify the "auto" > > > > value over time. After that, we could consider making "auto" the default. > > > > That said, I am not particularly strict about following this approach. > > > We cannot really set efi as the default, as it would break when > > > booting on legacy BIOS systems. > > > > > > We could take only patch 1 and leave patch 2 after Xen 4.20 has > > > branched, but at that point I would see little benefit in having just > > > patch 1. > > I don't see a lot of benefit of comitting only the one patch either. > > > > > > > I don't have a strong opinion, but downstreams have been complaining > > > about Xen behavior regarding the usage of EFI_GET_TIME, so it might be > > > good to not ship yet another release with such allegedly broken > > > behavior. > > Agree with that. As  I mentioned above I consider it as a bug and based on > > that several mentioned above downstreams have the similar patch I could consider > > that as tested approach so .. > > > Let me know what you think, as I would need a formal Release-Ack if > > > this is to be committed. > > ... R-Acked-by: Oleksii Kurochko. > > Sorry for the noise. > > I missed to add that it would also be nice to mention IMO ( that now we have wallclock parameter ) > in CHANGELOG so downstreams will receive "notification" that Xen provides a workaround for the mentioned > issue in the patch series. Indeed. Would you be OK with adding the following chunk to patch 2? diff --git a/CHANGELOG.md b/CHANGELOG.md index 8507e6556a56..1de1d1eca17f 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) leaving this to the guest kernel to do in guest context. - On x86: - Prefer ACPI reboot over UEFI ResetSystem() run time service call. + - Prefer CMOS over EFI_GET_TIME as time source. - Switched the xAPIC flat driver to use physical destination mode for external interrupts instead of logical destination mode. @@ -24,6 +25,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) - Support for LLC (Last Level Cache) coloring. - On x86: - xl suspend/resume subcommands. + - `wallclock` command line option to select time source. ### Removed - On x86: