Re: "Richard Stallman Announces C Reference"

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.lang.c++
Subject	Re: "Richard Stallman Announces C Reference"
Date	2022-09-18 12:22 +0200
Organization	A noiseless patient Spider
Message-ID	<tg6rh0$fml9$1@dont-email.me> (permalink)
References	(11 earlier) <tfr0f0$2ppo$1@nyheter.lysator.liu.se> <tfrv41$2rkif$1@dont-email.me> <tfsae7$iac$1@nyheter.lysator.liu.se> <tfsmhf$2vqod$1@dont-email.me> <tg2lik$29qi$1@nyheter.lysator.liu.se>

Show all headers | View raw

On 16/09/2022 22:16, Andreas Kempe wrote:
> Den 2022-09-14 skrev David Brown <david.brown@hesbynett.no>:
>> On 14/09/2022 12:29, Andreas Kempe wrote:
>>> Den 2022-09-14 skrev David Brown <david.brown@hesbynett.no>:
>>>> On 14/09/2022 00:33, Andreas Kempe wrote:
>>>>> Den 2022-09-13 skrev Muttley@dastardlyhq.com <Muttley@dastardlyhq.com>:
>>>>>> On Mon, 12 Sep 2022 20:32:21 +0200
>>>>>> Bo Persson <bo@bo-persson.se> wrote:
>>>>>>> On 2022-09-12 at 17:58, Muttley@dastardlyhq.com wrote:
>>>>>>>>> my_class f(x);
>>>>>>>>
>>>>>>>> And if that instance has virtual functions where will the VFT go and what
>>>>>>>> allocates it? Ditto any non primitive types which may cause an implcit
>>>>>>> cascade
>>>>>>>> of allocations.
>>>>>>>
>>>>>>> Just don't see how we know that int y = f(x); doesn't call other
>>>>>>> functions that allocate structs on the heap? Structs that contain
>>>>>>
>>>>>> It may well do, but you can at least look at them to see how and kernel authors
>>>>>> are extremely careful about how they allocate dynamic memory. Meanwhile
>>>>>> who knows if std::string s = "hello" will allocate on the heap or if it'll
>>>>>> use its small reerved amount of stack.
>>>>>>
>>>>>>
>>>>>
>>>>> In my view, this is not a language problem as much as a standard
>>>>> library implementation problem. As have been brought up earlier, you
>>>>> don't use the normal user space libc in the kernel for C code, but
>>>>> have parts of the standard library implemented in a way to make it fit
>>>>> the kernel.
>>>>>
>>>>> To seriously bring C++ into the kernel world, one would have to do the
>>>>> same. That is, pick functions from the standard library that make
>>>>> sense in the kernel and implement them to work there. One such thing
>>>>> could of course be an std::string without hidden heap allocations.
>>>>>
>>>>> I, and doubtlessly many others, have long toyed with the idea that
>>>>> kernel programming, Linux or *BSD is what I'm familiar with, could be
>>>>> made simpler with a language that supports object oriented programming
>>>>> instead of using C structs with function pointers. The possibility of
>>>>> doing RAII would also be nice. Whether that language should be C++ is
>>>>> another question and I don't have a good answer.
>>>>
>>>> When working on an OS kernel, there are lots of things in the C standard
>>>> library that you avoid, and there is no difference in regard to C++.  It
>>>> has a lot in common with embedded development, and that is often done in
>>>> C++.  With the software I write, on microcontrollers, I am quite happy
>>>> to use C++, but I am careful about the features I use.  Exceptions are
>>>> disabled, virtual inheritance is out (virtual functions are used with
>>>> caution), and there is rarely a good enough reason for anything
>>>> involving dynamic memory in my code.
>>>>
>>>
>>> What size are we talking about? In a professional setting, I've only
>>> worked with embedded systems large enough to run Linux.
>>
>> Smaller than that - usually a /lot/ smaller.  I tend to think of
>> "embedded Linux systems" as primarily /Linux/ systems, rather than
>> primarily /embedded/ systems.  Some people prefer "resource constrained
>> embedded systems" as an alternative name.
>>
>> Basically, I am considering systems where you have a single statically
>> linked program.  (You might have sometimes have an extra boot program,
>> or updater, or test program - but the normal mode of operation is one
>> program.)
>>
> 
> I guess the term embedded is a bit diluted these days with how
> powerful SoCs have become.

Yes, indeed.  There have always been powerful embedded systems, with big 
processors running big OS's, but they used to be very much in the 
minority.  Now you can put a Pi Zero running Linux in anything.  The key 
distinction, I think, whether the system is running a single statically 
linked program as its main task (either bare bones, or with an RTOS of 
some kind).

> 
> Working on projects for very small processors, I've only used C or
> assembly and my main experience is using PICs. I have toyed with the
> idea of using C++, but there isn't really any free C++ compilers PICs
> as far as I've found.
> 

The PICs (and by that I assume you mean the 8-bit devices, not the PIC32 
chips which have MIPS cores) have always had quite limited tools - they 
are not well suited to C coding, never mind C++.  The only 8-bit 
microcontroller for which C++ is a reasonable option is the AVR, for 
which the most common compiler is gcc.  The core language is well 
supported, but much of the library is very limited - including 
language-support code for things like exceptions.

> Thank you for an informative reply!
> 
>> [...]

Thread

"Richard Stallman Announces C Reference" Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-09 12:49 -0500
  Re: "Richard Stallman Announces C Reference" scott@slp53.sl.home (Scott Lurndal) - 2022-09-09 19:03 +0000
  Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-10 18:16 +0200
    Re: "Richard Stallman Announces C Reference" scott@slp53.sl.home (Scott Lurndal) - 2022-09-10 17:04 +0000
      Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-11 08:29 +0000
      Re: "Richard Stallman Announces C Reference" Manfred <noname@add.invalid> - 2022-09-24 16:24 +0200
        C++ is for real, C is just a toy (Was: "Richard Stallman Announces C Reference") gazelle@shell.xmission.com (Kenny McCormack) - 2022-09-24 15:54 +0000
          Re: C++ is for real, C is just a toy (Was: "Richard Stallman Announces C Reference") Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-24 18:07 +0200
    Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-11 08:29 +0000
      Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-11 11:16 +0200
        Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-11 09:44 +0000
          Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-11 13:42 +0200
            Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-11 15:44 +0000
              Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-11 17:55 +0200
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-11 16:17 +0000
                Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-11 18:22 +0200
                Re: "Richard Stallman Announces C Reference" "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-11 12:41 -0700
                Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-12 06:10 +0200
                Re: "Richard Stallman Announces C Reference" "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-12 00:27 -0700
              Re: "Richard Stallman Announces C Reference" Bo Persson <bo@bo-persson.se> - 2022-09-12 09:18 +0200
                Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-12 09:42 +0200
                Re: "Richard Stallman Announces C Reference" Bo Persson <bo@bo-persson.se> - 2022-09-12 12:05 +0200
                Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-12 12:12 +0200
                Re: "Richard Stallman Announces C Reference" Manfred <noname@add.invalid> - 2022-09-24 16:31 +0200
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-12 15:58 +0000
                Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-12 18:48 +0200
                Re: "Richard Stallman Announces C Reference" Bo Persson <bo@bo-persson.se> - 2022-09-12 20:32 +0200
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-13 13:27 +0000
                Re: "Richard Stallman Announces C Reference" Andreas Kempe <kempe@lysator.liu.se> - 2022-09-13 22:33 +0000
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-14 06:04 +0000
                Re: "Richard Stallman Announces C Reference" Andreas Kempe <kempe@lysator.liu.se> - 2022-09-14 10:38 +0000
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-14 12:21 +0000
                Re: "Richard Stallman Announces C Reference" Michael S <already5chosen@yahoo.com> - 2022-09-15 12:15 -0700
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-16 06:02 +0000
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-16 10:37 +0000
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-16 11:05 +0000
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-16 13:18 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-16 16:00 +0200
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-16 15:16 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-18 12:13 +0200
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-19 05:45 +0000
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-19 08:33 +0000
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-19 10:41 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-19 13:48 +0200
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-19 15:22 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-16 13:10 +0200
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-19 05:51 +0000
                Re: "Richard Stallman Announces C Reference" Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-19 12:27 -0700
                Re: "Richard Stallman Announces C Reference" "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-16 11:19 -0700
                Re: "Richard Stallman Announces C Reference" Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-16 06:56 -0700
                Re: "Richard Stallman Announces C Reference" scott@slp53.sl.home (Scott Lurndal) - 2022-09-16 14:29 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-16 17:04 +0200
                Re: "Richard Stallman Announces C Reference" Michael S <already5chosen@yahoo.com> - 2022-09-16 08:24 -0700
                Re: "Richard Stallman Announces C Reference" Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-09-16 09:00 -0700
                Re: "Richard Stallman Announces C Reference" Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2022-09-15 00:54 +0100
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-15 05:31 +0000
                Re: "Richard Stallman Announces C Reference" Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2022-09-15 10:19 +0100
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-22 12:41 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-14 09:16 +0200
                Re: "Richard Stallman Announces C Reference" Andreas Kempe <kempe@lysator.liu.se> - 2022-09-14 10:29 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-14 15:55 +0200
                Re: "Richard Stallman Announces C Reference" Andreas Kempe <kempe@lysator.liu.se> - 2022-09-16 20:16 +0000
                Re: "Richard Stallman Announces C Reference" Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-16 16:55 -0500
                Re: "Richard Stallman Announces C Reference" scott@slp53.sl.home (Scott Lurndal) - 2022-09-16 22:21 +0000
                Re: "Richard Stallman Announces C Reference" Andreas Kempe <kempe@lysator.liu.se> - 2022-09-17 14:52 +0000
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-19 06:06 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-18 12:34 +0200
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-18 12:22 +0200
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-19 06:11 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-19 10:14 +0200
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-14 12:12 +0000
                Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-14 15:58 +0200
              Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-13 06:47 +0000
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-13 13:29 +0000
                Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-14 05:56 +0000
                Re: "Richard Stallman Announces C Reference" Muttley@dastardlyhq.com - 2022-09-14 09:37 +0000
          boost::intrusive. Was: "Richard Stallman Announces C Reference" Michael S <already5chosen@yahoo.com> - 2022-09-11 09:51 -0700
            Re: boost::intrusive. Was: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-11 18:55 +0200
        Re: "Richard Stallman Announces C Reference" scott@slp53.sl.home (Scott Lurndal) - 2022-09-11 16:26 +0000
          Re: "Richard Stallman Announces C Reference" Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-11 18:35 +0200
        Re: "Richard Stallman Announces C Reference" Opus <ifonly@youknew.org> - 2022-09-12 19:22 +0200
          Re: "Richard Stallman Announces C Reference" legalize+jeeves@mail.xmission.com (Richard) - 2022-09-22 19:24 +0000
  Re: "Richard Stallman Announces C Reference" Michael S <already5chosen@yahoo.com> - 2022-09-10 12:56 -0700
    Re: "Richard Stallman Announces C Reference" Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-10 15:53 -0700
    Re: "Richard Stallman Announces C Reference" "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-09-11 07:07 +0200
      Re: "Richard Stallman Announces C Reference" Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-11 16:17 -0700
    Re: "Richard Stallman Announces C Reference" David Brown <david.brown@hesbynett.no> - 2022-09-11 13:50 +0200
      Re: "Richard Stallman Announces C Reference" Michael S <already5chosen@yahoo.com> - 2022-09-11 05:53 -0700
    Re: "Richard Stallman Announces C Reference" Juha Nieminen <nospam@thanks.invalid> - 2022-09-12 05:47 +0000
  Re: "Richard Stallman Announces C Reference" Manu Raju <MR@invalid.invalid> - 2022-09-11 00:01 +0100
    Re: "Richard Stallman Announces C Reference" Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-10 16:26 -0700
  Re: "Richard Stallman Announces C Reference" legalize+jeeves@mail.xmission.com (Richard) - 2022-09-22 19:21 +0000

csiph-web