Hi, On Thu, Oct 26, 2017 at 12:37 PM, Jim Hall <jh...@freedos.org> wrote: >> On Thu, 26 Oct 2017, David McMackins wrote: >> >>> I have been informed that gcc has a -m16 flag that actually outputs >>> binaries that can run in 16-bit mode. Is there then anything stopping >>> FreeDOS from being compiled fully with gcc?
It took a bit of searching, but I vaguely remembered this being discussed before: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59672 Long story short: it seems to be only meant to simplify automatically using (BinUtils) ".code16gcc" in sources without resorting to messy hacks. It's mainly used by Linux kernel devs (apparently), so only very limited and specific use, not fully general 16-bit support. >>> If not, why are we still using Watcom? Nobody has put in the work to convert to other compilers. (There's still support for TurboC and one or two others [DMC?] in the kernel but nothing better / free-r than OpenWatcom.) There's also little concrete advantage to using, say, DJGPP, besides just bragging how "free" we are. It also might make the kernel 386+ only. (But, honestly, I wish somebody would indeed convert it to GCC/DJGPP, even if 386+ only. That does not preclude us from also supporting 16-bit builds at the same time.) Maybe SmallerC would be a better target? It's 386+ only but fairly good, free/libre, compiles itself ... but it doesn't support Compact model (though it does support Huge). > On Thu, Oct 26, 2017 at 8:48 AM, Steve Nickolas <usots...@buric.co> wrote: >> Pretty sure that GCC, if it supports 8088/286 at all, can't handle all the >> memory models (this was, iirc, DJ Delorie's justification for why DJGPP >> would only do 386+ binaries - think he said it would at best only support >> the tiny and small models, and some of the FreeDOS tools need other memory >> models.) Tiny and Small are better than nothing. AFAIK, DOS-C used to use Small model. FreeCOM also uses Small model too, IIRC. There is one guy continuing the work of another guy with experimental (out of tree?) 8086-elf support for GCC ("GCC IA16"), and it works, but it still has a ways to go to do better than Tiny and Small (.COM only). FreePascal (since 3.0.0 in 2015, currently at 3.0.2 with 3.0.4 coming soon) has i8086-msdos cross-target nowadays. It supports all memory models (Tiny, Small, Medium, Compact, Large ... except Huge, that's trunk only, aka 3.1.1 or whatever, unofficial snapshots only). Since it supports "{$mode tp}" (aka, "-Mtp") and Turbo Pascal was widely popular in DOS circles, I think that's a reasonable choice for porting (old or new) code to DOS. (It's cross only, for now, but you can host the Win32 .EXEs under HX/DOS.) > It would be interesting to try GCC in 16-bit mode. I wonder if this > works in the DJGPP version, which is the version of GCC (5.5) that > runs on DOS. The latest DJGPP is 2.05 (stable/current since 2015), and their latest GCC is 7.2.0. But they also have builds of older supported versions, e.g. 6.4.0 and 5.5.0 (which you're referring to here), for completeness. We're not stuck to 5.5.0, in case anyone misunderstood. Both the Zip Picker and mini FAQ both point to 7.2.0 as latest (with BinUtils 2.29.1). There is apparently partial (unofficial?) support for --gc-sections now, too. But all of that is still 32-bit DPMI only (for now). There has not been any attempt to build "GCC IA16" suite with DJGPP as host. > Steve raises a good point about the memory models. DOS compilers > (including Watcom) can generate different executable memory models, > suitable for different sizes of applications. Some FreeDOS programs > use Tiny memory model, for example. > > David: would you like to try compiling some FreeDOS programs under GCC > using -m16 flag? The Kernel is big project, so starting with some > utilities would be a good first experiment. All of the TurboC ports should be deprecated in lieu of OpenWatcom (or, better yet, DJGPP). FreeDOS needs to be "Free". I know some here have a hard time accepting this, but we really need to focus on using Free tools. That doesn't mean you can't also support others at the same time. It also doesn't mean that we're forcing 386+ DJGPP as exclusive main compiler. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
