Re: [Libguestfs] [PATCH v2v 0/5] convert: Find out if Windows guest is expecting BIOS localtime or UTC

On 9/25/23 16:04, Richard W.M. Jones wrote: > [Alice: See patch 2] > > [This patch is a bit rough, it could do with better commit messages > and some tests. Please test it to see if it solves the Windows > conversion issue described in the thread below.] > > We currently do not set any <clock/> field in guest output. Most > Windows guests expect the BIOS to be set to localtime, whereas almost > all Linux guests would expect it to be set to UTC. It is also > possible to configure a Windows guest to expect BIOS set to UTC. > > The default is usually BIOS set to UTC, so for many Windows guests > this would be wrong. This specifically may cause problems when > scheduling qemu-ga installation, see the thread here: > > https://listman.redhat.com/archives/libguestfs/2023-September/thread.html... > > but could cause other general issues with time in the guest. > > One way to implement this would be to copy the source hypervisor > information across; however I'm not confident this information is read > correctly. A better way is to read out what the guest is expecting > from the Windows registry. (For Linux we just assume BIOS is always > UTC, since that's the default for almost any Linux guest which hasn't > been dual-booted with Windows, which for VMs would be incredibly > rare.) I think the word "BIOS" is incorrectly used all over the series; I'd rather say "RTC" / "real time clock".