On Fri, 2017-03-10 at 01:01 +0300, Stas Sergeev wrote: > 09.03.2017 03:46, Ricardo Neri пишет: > > On Wed, 2017-03-08 at 17:08 +0300, Stas Sergeev 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. > >> Yes, this is the case. > >> But at least in the past there was an attempt to > >> support SLDT as it is used by an ancient pharlap > >> DOS extender (currently unsupported by dosemu1/2). > >> So how difficult would it be to add an optional > >> possibility of delivering such SIGSEGV to userspace > >> so that the kernel's dummy emulation can be overridden? > > I suppose a umip=noemulation kernel parameter could be added in this > > case. > Why? > It doesn't need to be global: the app should be > able to change that on its own. Note that no app currently > requires this, so its just for the future, and in the > future the app can start using the new API for this, > if you provide one. Right, I missed this detail. Then, yes the API should allow only one app to relay the SIGSEGV. > > > >> It doesn't need to be a matter of this particular > >> patch set, i.e. this proposal should not trigger a > >> v7 resend of all 21 patches. :) But it would be useful > >> for the future development of dosemu2. > > Would dosemu2 use 32-bit processes in order to keep segmentation? If it > > could use 64-bit processes, emulation is not used in this case and the > > SIGSEGV is delivered to user space. > It does use the mix: 64bit process but some segments > are 32bit for DOS code. Do you mean that dosemu2 will start as a 64-bit process and will jump to 32-bit code segments? My emulation code should work in this case as it will use segmentation in 32-bit code descriptors. Is there anything else needed? Thanks and BR, Ricardo -- 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
