On Fri, Mar 10, 2017 at 3:33 AM, Stas Sergeev <stsp@xxxxxxx> wrote: > 10.03.2017 05:39, Andy Lutomirski пишет: > >> On Thu, Mar 9, 2017 at 2:10 PM, Stas Sergeev <stsp@xxxxxxx> wrote: >>> >>> 09.03.2017 04:15, Ricardo Neri пишет: >>> >>>> On Wed, 2017-03-08 at 08:46 -0800, Andy Lutomirski wrote: >>>>> >>>>> On Wed, Mar 8, 2017 at 8:29 AM, Stas Sergeev <stsp@xxxxxxx> wrote: >>>>>> >>>>>> 08.03.2017 19:06, Andy Lutomirski пишет: >>>>>>> >>>>>>> On Wed, Mar 8, 2017 at 6:08 AM, Stas Sergeev <stsp@xxxxxxx> wrote: >>>>>>>> >>>>>>>> 08.03.2017 03:32, Ricardo Neri пишет: >>>>>>>>> >>>>>>>>> These are the instructions covered by UMIP: >>>>>>>>> * SGDT - Store Global Descriptor Table >>>>>>>>> * SIDT - Store Interrupt Descriptor Table >>>>>>>>> * SLDT - Store Local Descriptor Table >>>>>>>>> * SMSW - Store Machine Status Word >>>>>>>>> * STR - Store Task Register >>>>>>>>> >>>>>>>>> This patchset initially treated tasks running in virtual-8086 >>>>> >>>>> mode as a >>>>>>>>> >>>>>>>>> special case. However, I received clarification that DOSEMU[8] >>>>> >>>>> does not >>>>>>>>> >>>>>>>>> support applications that use these instructions. >>>>>>> >>>>>>> Can you remind me what was special about it? It looks like you >>>>> >>>>> still >>>>>>> >>>>>>> emulate them in v8086 mode. >>>>>> >>>>>> Indeed, sorry, I meant prot mode here. :) >>>>>> So I wonder what was cited to be special about v86. >>>> >>>> Initially my patches disabled UMIP on virtual-8086 instructions, without >>>> regards of protected mode (i.e., UMIP was always enabled). I didn't have >>>> emulation at the time. Then, I added emulation code that now covers >>>> protected and virtual-8086 modes. I guess it is not special anymore. >>> >>> But isn't SLDT&friends just throw UD in v86? >>> How does UMIP affect this? How does your patch affect >>> this? >> >> Er, right. Ricardo, your code may need fixing. But don't you have a >> test case for this? > > Why would you need one? > Or do you really want to allow these instructions > in v86 by the means of emulation? If so - this wasn't > clearly stated in the patch description, neither it was > properly discussed, it seems. What I meant was: if the patches incorrectly started making these instructions work in vm86 mode where they used to cause a vm86 exit, then that's a bug that the selftest should have caught. -- To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
