In article <local.mail.freebsd-hackers/[EMAIL PROTECTED]> you write:
>Is there a way to make VM86 interrupt calls from userland? The reason I'm
>asking is that in order to get my video card (Savage/IX) working in X
>properly, I need to make a couple of VESA int10 calls (or somehow obtain
>the programming specs for the card and do this the right way). Anyway,
>what I have tried is using the syscons ioctl()'s, which doesn't work here.
>Right now what I've done is modified src/sys/i386/i386/vm86.c to enable the
>VM86_INTCALL bit (and added a check for uid), and just called i386_vm86
>from userland. This seems to work fine, but I want to know
>
>1) Is there already some standard way to do this that I missed? The man
> page for i386_vm86 mentions sigreturn(), but I'm not sure if that will
> do what I want, plus I don't know how to use it anyway...
>2) There was probably a reason the VM86_INTCALL stuff was #if'ed out... but
> I looked around the lists and cvs logs to see if one was mentioned and
> found none. This seems to work and I don't see how anything bad could
> come from this -- is it possible that this be enabled by default?
>3) Or would the whole problem be solved more correctly by extending the
> ioctl by adding something like FBIO_SETMODE_ONLY where syscons would
> only switch the mode and not bother setting up the renderer or emulator?
I added VM86_INTCALL while developing the vm86 system for this very
reason; so I could make vm86 calls from userland. However, it was
turned off before it was initially committed, since it could probably
open up a security hole or worse.
My feeling is that this functionality probably belongs in the kernel
(point #3), but as a workaround, adding a root capability check and
then enabling the vm86 functionality is probably acceptable.
--
Jonathan
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