[vbox-dev] Removing code only used by no longer supported hosts (was Opportunity to significantly shrink the vboxsf Linux driver)

Knut St. Osmundsen knut.osmundsen at oracle.com
Tue Aug 8 14:56:16 UTC 2017

Hi Hans,

vgdrvInitFixateGuestMappings cannot be removed, that is still used when
running guests in raw-mode.  Raw-mode still have its uses even on hosts
with hardware virtualization support.  Like for instance running VBox
inside a guest OS (i.e. nested virtualization without needing nested
hardware virtualization), or when some other hypervisor don't want to
share VT-x/AMD-V with us.

vgdrvReportGuestInfo can probably drop the pre 3.2.51 else code path
without anything bad happening.


On 2017-08-08 4:23 PM, Hans de Goede wrote:
> Hi,
> On 07/25/2017 11:06 AM, Michael Thayer wrote:
> > 13.07.2017 16:42, Michael Thayer wrote:
> >> 10.07.2017 12:29, Hans de Goede wrote:
> >> [Patch to shared folder code proposed by Hans to reduce the line count
> >> of the Linux driver.]
> >>
> >> I reviewed the patch and made a few changes.  Not yet tested on any
> >> platform, but I am posting my adjusted version so that other people
> can
> >> test, including on FreeBSD and Haiku which I cannot do easily.  Note
> >> that this applies to the normal VirtualBox tree, not to the packaged
> >> Linux driver.
> > I redid the patch again, after realising that the non-physical-page
> path
> > was for supporting VirtualBox 3.0 and older on the host, which we have
> > not tested or supported for a long time.  Therefore
> > VbglR0CanUsePhysPageList() could be removed altogether.
> Ok, so I assume that similar checks to use physical page-lists can
> be removed from vboxguest too ?
> And talking about removing support for old features, are hosts
> without intel-vt or the amd equivalent still supported; if not then
> I think that vgdrvInitFixateGuestMappings can be removed ?
> And what about vgdrvReportGuestInfo() can that be modified to
> simply always first call VMMDevReq_ReportGuestInfo2 and then
> VMMDevReq_ReportGuestInfo or are some of the paths checking for
> needed ?
> Regards,
> Hans
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