On Thu, Nov 26, 2020 at 01:51:43PM +0100, Laszlo Ersek wrote: > On 11/26/20 12:09, Michael S. Tsirkin wrote: > > On Wed, Nov 25, 2020 at 09:13:22PM +0100, Antoine Damhet wrote: > >> On Wed, Nov 25, 2020 at 11:04:55AM -0500, Michael S. Tsirkin wrote: > >>> On Wed, Nov 25, 2020 at 01:32:51PM +0000, Richard W.M. Jones wrote: > >>>> On Wed, Nov 25, 2020 at 02:27:11PM +0100, Antoine Damhet wrote: > >>>>> Hello, > >>>>> > >>>>> We recently found out that some softwares are effectively crashing > >>>>> when they detect qemu's `OEM ID` or `OEM table ID` in the ACPI tables. > >>>>> > >>>>> I see no reason not to expose the setting to the user/command-line. A > >>>>> previous patch has been submitted in 2015[1] but did not get through > >>>>> because (if I understand correctly) using the IDs on the `SLIC`, `BXPC` > >>>>> and `RSDT` tables were enough at the time. > >>>>> > >>>>> If you agree, I am willing to forward port the patches of M. Jones but I > >>>>> need to ask how it would work `Signed-Off`-wise ? > >>>> > >>>> On this point, the patch I sent was actually written by > >>>> Michael Tokarev, I was only trying to get them upstream. > >>>> > >>>> Rich. > >>> > >>> I think at least one of the issues is that e.g. UEFI at least > >>> seems to assume unique OEM table IDs e.g. for SSDTs. > >>> > >>> So let's try to be more specific please, which software > >>> crashes, what does it want to see and in which table. > >> > >> I'm sorry I cannot give you the name of the crashing software due to a > >> company policy. But I can tell you that if either `BOCHS ` or `BXPC` is > >> present in any of the tables it will crash. Any (or at least the few > >> that I threw at it) other string will work so it seems it's some kind > >> of DRM-related hypervisor detection. > > > > Hmm I'm not sure how far we want to go with this. If software vendors > > want to detect a hypervisor there will always be a way. > > How are we sure we are not starting an arms race here? > > > > Also which of the IDs matter? OEMID? OEM Table ID? Creator ID? > > > > > >> As for the uniqueness of the table IDs, I guess it would be sane to keep > >> the same pattern (id+table sig) but allowing the first 4 bytes to be > >> overridden. > >> > >> [...] > > > > It's certainly possible, it's just very specific to just this DRM scheme. > > Not sure what's a better way to do it: > > qemu -acpidefault oem_id=ABCD,oem_table_id=EFGHIJKL > > is probably going too far since then table IDs are not unique. > > > > Also I'd probably use machine properties for this, the need here > > is baroque enough that we don't want a dedicated option. > > Minimally, I dislike the partial overlap with the existent "-acpitable" > switch. > > Thanks > Laszlo
Well the existing -acpitable is very powerful and easy to break guests with, it can not really be fully supported. > > > >> > >> -- > >> Antoine 'xdbob' Damhet > >
