OK, thanks for the prompt reply, Andy! I'll try your sysfs suggestion. Let me just add a bit of CCs to get more people involved. I believe the ram size involvement makes this smell like a bug, plus it looks like a regression. Not that I am going to suffer much (this pass-through stuff always breaks in a million of different ways, I'll probably just remove it), but its still a very questionable change IMO.
29.10.2016 00:26, Andy Lutomirski пишет: > On Fri, Oct 28, 2016 at 2:18 PM, Stas Sergeev <s...@list.ru> wrote: >> 29.10.2016 00:05, Andy Lutomirski пишет: >> >>> On Fri, Oct 28, 2016 at 2:03 PM, Stas Sergeev <s...@list.ru> wrote: >>>> Hello. >>>> >>>> For the long time dosemu used /dev/mem for vga pass-through. >>>> Now it appears /dev/mem has this check: >>>> http://lxr.free-electrons.com/source/drivers/char/mem.c#L51 >>>> which prevents an accesses to PCI memory regions if the >>>> "high_memory" points low enough. It seems "high_memory" >>>> just points to the end of the physical ram, so depending on >>>> the ram size you either can access PCI devices or you get >>>> EFAULT. >>>> Was it wrong to use /dev/mem for accessing the PCI devices? >>>> How should I do that now? >>>> >>> What is DOSEMU trying to do here? Access the framebuffer? >>> >>> ISTM it would be better to use the DRM or FB layer directly (just map >>> the framebuffer itself) or, if necessary, use VFIO. >> Yes, framebuffer. >> Mapping fb directly is not really an option because dosemu does >> its own modesetting when you do vga pass-through. So it is >> usually started that way with "nomodeset=1" and w/o fb. >> Yes, some crazy people try the pass-through even out of fb >> console, but that's weird (the problem is most SDL2 builds do >> not have directfb backend compiled in, otherwise we could >> just use SDL rendering on top of fb). >> >> The thing is, I needed (for testing purposes, unrelated to dosemu) >> some quick way to access the PCI memory space, and to my surprise I >> couldn't do that with /dev/mem. Was this really disallowed intentionally? > I believe so. > > Try the /sys/devices/.../resource? and resource?_wc files. > > --Andy > ------------------------------------------------------------------------------ The Command Line: Reinvented for Modern Developers Did the resurgence of CLI tooling catch you by surprise? Reconnect with the command line and become more productive. Learn the new .NET and ASP.NET CLI. Get your free copy! http://sdm.link/telerik _______________________________________________ Dosemu-devel mailing list Dosemu-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dosemu-devel
