Date: Wed, 7 Oct 2020 12:40:19 +0530 From: Kamal Prasad <kamalpr@gmail.com> To: Warner Losh <imp@bsdimp.com> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org> Subject: Re: generic q on freebsd Message-ID: <C4AE5DDB-005E-45B1-8BF6-FC28647B4E90@gmail.com> In-Reply-To: <CANCZdfoaZYnsb6str64ezF0O4ORSQG%2BqMh9r0%2B42GqEQjBThOg@mail.gmail.com> References: <CAK=yUGJG=oVfy7XfnMkXB6XRBjbYhaVR8Zdv7R5wGqKjB=425Q@mail.gmail.com> <CANCZdfoaZYnsb6str64ezF0O4ORSQG%2BqMh9r0%2B42GqEQjBThOg@mail.gmail.com>
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Thanks. Why is it difficult to port the C++ runtime to the kernel? I = mean what is the technological hurdle? thanks -kamal On Oct 6, 2020, at 10:53 PM, Warner Losh <imp@bsdimp.com> wrote: >=20 > On Tue, Oct 6, 2020, 11:03 AM Kamal R. Prasad <kamalpr@gmail.com> = wrote: >=20 >> hello, >>=20 >> i am curious if it is possible to compile c++ code inside the freebsd >> kernel. >>=20 >=20 >=20 > Possible? Yes, with restrictions. Easy? No. >=20 > There are a number of restrictions on doing this. There is no C++ = runtime > support provided in stock FreeBSD. You have to write your own, or find > someone else that has published theirs. And the code is likely to be > compiler dependent. People have done it and talked or blogged about = it. >=20 > Generally, if you don't use exceptions, templates, RTTI, expressions = that > result in the automatic allocation of objects, have large objects (> = 1k) on > the stack, etc, it may be possible. I tried it in the 90s and had to = write > just a few routines to make simple classes work, but there's a lot of > dragons here and very little C++ code is written these days w/o = reference > to the standard libraries, which aren't present in the kernel. >=20 > Some googling turns up: > https://github.com/adamlsd/libcpp.ko from 6 years ago > https://lists.freebsd.org/pipermail/freebsd-arch/2018-June/019069.html = has > some details from 2 years ago about command line args you might need. >=20 > Many have tried. Few have succeeded. Those that have write all their = code > to conform to a subset of the language. Few have had success moving = C++ > code for other purposes into the kernel, though if it was written = using the > proposed (but never ratified) eC++ (embedded subset), then chances are > greater. >=20 > Good luck >=20 > Warner > _______________________________________________ > freebsd-arm@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-arm > To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org"
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