This topic is mainly for developers of FreeBSD that develop in machine code, until even in binary code.

[françai s]

Someone?

2014-11-20 12:33 GMT-02:00 françai s <romapera15 at gmail.com>:

> This subject is irresistible to me,I like so much of this issue that get
> out tears out of my eyes.
>
> This topic is mainly for developers of FreeBSD that develop in machine
> code, until even in binary code.
>
> A FreeBSD developer told me via private message that the  the most FreeBSD
> developers don’t develop in machine code, in other words, the  minority
> FreeBSD developers develop in machine code, until even in binary code.
>
> He told me this:
>
> "We either create a macro expands to something like ".word <foo> “ or
> sometimes the .word <foo> is just hard coded inline when there’s only going
> to be one of them. Sometimes we expose them both in assembly and in C code,
> in which case what we do varies a bit to accommodate the different
> language’s syntax. It is rare, but has happened, that we only expose it to
> C code.
>
> Generally, though, we try to add support for the opcodes to gas so that we
> get the constraint testing it does (making sure the opcode is supported at
> the level you are compiling, making sure it isn’t in a delay slot or
> violating some other precondition for its use)."
>
> "You pointed me at macros that defined operations in terms of opcodes the
> assembler didn’t understand with the workaround being the assembler
> directive using .word followed by by some hex value to encode the opcode."
>
> "Most developers of FreeBSD don’t  write directly in machine code in
> FreeBSD development, and don’t care. Some developers use the marcos that I
> described sometimes when doing specific, low-level coding. A handful of
> developers create the marcos directly or use the .word directives in their
> work to make certain things work that cannot work otherwise.
>
> People generally don’t write in raw machine opcodes. That is independent
> of FreeBSD.
>
> However, a few, specialized people will find the need to do it from time
> to time. Usually because they are porting FreeBSD to a newer processor that
> needs newer opcodes to do context switching, optimize interrupt handling,
> code with a new type of cache coherency, etc. These people look up the
> assembler in the docs from the vendor and then create the .word workaround
> to make sure things work. If they have the time, they may add it to our
> somewhat ancient gas assembler as well."
>
> "Almost nobody writes directly in binary. There are some exceptions,
> sometimes though."
>
> The following link leads to tutorial that teaches programming Assembly in
> to FreeBSD:
> http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/x86.html
>
> Also exist tutorial that teaches programming in machine code to FreeBSD?
>