Date: Mon, 10 Oct 2016 20:17:36 -0300 From: =?UTF-8?Q?fran=C3=A7ai_s?= <romapera15@gmail.com> To: freebsd-hackers@freebsd.org Subject: What are the codes that contain the marcos that are created directly or the .word directives that are used in their work to make certain things work that cannot work otherwise? Message-ID: <CAK_6RwdMpJDktahiNiRSD-75pxAnaUgyBmWw=KwAx2xD4haEmQ@mail.gmail.com>
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It has come to my attention the following: "The minority of FreeBSD developers either create a macro expands to something like ".word <foo> =E2=80=9C or sometimes the .word <foo> is just = hard coded inline when there=E2=80=99s only going to be one of them, sometimes e= xpose them both in assembly and in C code, in which case what we do varies a bit to accommodate the different language=E2=80=99s syntax. It is rare, but has happened, that we only expose it to C code. Generally, though, the minority of FreeBSD developers try to add support for the opcodes to gas so that get the constraint testing it does (making sure the opcode is supported at the level you are compiling, making sure it isn=E2=80=99t in a delay slot or violating some other precondition for its = use). People generally don=E2=80=99t write in raw machine opcodes. That is indepe= ndent 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." What are the codes that contain the marcos that I described above sometimes when doing specific, low-level coding? What are the codes that contain the marcos that are created directly or the .word directives that are used in their work to make certain things work that cannot work otherwise?
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