+ Do the work in a separate branch, not on mob which people use for production
"Christian Jullien" <eli...@orange.fr> wrote: > + project duration > > -----Original Message----- > From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=orange...@nongnu.org] > On Behalf Of Christian Jullien > Sent: Tuesday, January 19, 2021 06:46 > To: tinycc-devel@nongnu.org > Subject: Re: [Tinycc-devel] enforced immutability - proposed research project > > Gentlemen, > I'm happy to see you have a lot of ideas. Here is what I propose: > - take time to think about the approach you want to implement this feature, > ask advices from maintainers if you like. > - move implementation discussion to another list > - THEN propose a research subject with: > * estimated compilation speed impact (goal/non goal) > * estimated execution speed impact (goal/non goal) > * availability/portability on OS/cpu/compiler (IMHO at least mainline > architectures, I would say Linux/[x64, aarch64, riscv 64], Windows x64 and > another un*x like *BSD) - Okay, riscv is not yet mainline but hope it will > soon. > * user interface (set using configure option, set using a compiler option, > new __attribute__ etc...) > * impact on current source code (mostly implemented in a new file, > dissimilated in source code with #if/#endif, with macro, ...) > * list gold ports (i.e. ports tested before any commits) and silver ports > (i.e. ports that also probably work after commits). > * nominate a coordinator for this project > - wait approval from maintainers. > > Sounds reasonable? > > Christian > > -----Original Message----- > From: Tinycc-devel [mailto:tinycc-devel-bounces+eligis=orange...@nongnu.org] > On Behalf Of Elijah Stone > Sent: Tuesday, January 19, 2021 02:44 > To: tinycc-devel@nongnu.org > Subject: Re: [Tinycc-devel] enforced immutability - proposed research project > > On Tue, 19 Jan 2021, Bruno Haible wrote: > > > MAP_FIXED is a portability nightmare nowadays, where most OSes implement > > address space randomization and put the shared libraries at arbitrary > > and random locations in the address space. You better stay away from it. > > > > The implementation I pointed to therefore doesn't use MAP_FIXED, just > > plain MAP_SHARED. > > The problem is, without a fixed offset between the mutable and immutable > spaces, certain desirable semantics become harder to implement. For > example, we want mutable and immutable references to the same object to > compare equal. > > One potential solution is to rely on overcommit. Map a giant memory > region, and then remap the second portion (using MAP_FIXED) to alias the > first half. (Using MAP_FIXED to overwrite existing address space mappings > _is_ a supported usage.) > > -E > > > _______________________________________________ > Tinycc-devel mailing list > Tinycc-devel@nongnu.org > https://lists.nongnu.org/mailman/listinfo/tinycc-devel > > > _______________________________________________ > Tinycc-devel mailing list > Tinycc-devel@nongnu.org > https://lists.nongnu.org/mailman/listinfo/tinycc-devel > > > _______________________________________________ > Tinycc-devel mailing list > Tinycc-devel@nongnu.org > https://lists.nongnu.org/mailman/listinfo/tinycc-devel _______________________________________________ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel