[vbox-dev] Expert options

Klaus Espenlaub klaus.espenlaub at oracle.com
Wed Aug 19 13:23:29 UTC 2015


Mario,

On 17.08.2015 15:09, Mario Lobo wrote:
> Hi;
>
> When typing VirtualBox --help, it prints these:
>
> [snip]
>
> Expert options:
> --disable-patm             disable code patching (ignored by
> AMD-V/VT-x)
> --disable-csam             disable code scanning (ignored
> by AMD-V/VT-x)
> --recompile-supervisor     recompiled execution of
> supervisor code (*)
> --recompile-user           recompiled execution of
> user code (*)
> --recompile-all            recompiled execution of all
> code, with disabled code patching and scanning
> --execute-all-in-iem       For debugging the interpreted execution
> mode.
> --warp-pct <pct>           time warp factor, 100% (= 1.0) =
> normal speed
>
> (*) For AMD-V/VT-x setups the effect is --recompile-all.
>
> I tried to find documentation for them but I couldn't. Nor there are
> any explanations on the User Manual.

Why should they be documented in detail? Even power users don't need 
them. In fact many of these options cause severe performance reduction 
or even non-working VMs.

> Could anybody point to an elaborate doc on them or what exactly do
> they do?

They're meant for developers who need to debug something in the software 
virtualization code.

Klaus

> Thanks



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