Date: Wed, 4 May 2016 03:58:40 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: John Baldwin <jhb@freebsd.org> Cc: Bruce Evans <brde@optusnet.com.au>, Pedro Giffuni <pfg@freebsd.org>, "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r298933 - in head: share/man/man9 sys/amd64/include sys/dev/acpica sys/dev/drm2 sys/dev/drm2/i915 sys/kern sys/sys sys/x86/acpica sys/x86/x86 Message-ID: <20160504031930.A3395@besplex.bde.org> In-Reply-To: <8989101.JIAk4LJusf@ralph.baldwin.cx> References: <201605021800.u42I0cjK084243@repo.freebsd.org> <c30f7a5a-1185-755d-ccf9-df7d071e3417@FreeBSD.org> <20160503152502.A939@besplex.bde.org> <8989101.JIAk4LJusf@ralph.baldwin.cx>
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On Tue, 3 May 2016, John Baldwin wrote: > On Tuesday, May 03, 2016 03:52:56 PM Bruce Evans wrote: >> On Mon, 2 May 2016, Pedro Giffuni wrote: >... >>> TBH, I thought so too, but I avoided applying such changes to headers, >>> and I haven't touched _bitset.h, >> >> _foo.h headers cannot use howmany() due to namespace pollution. >> >> _bitset.h was already broken, unless it is supposed to be kernel-only -- >> it uses howmany(). It is kernel-only according to its documention -- >> bitset is only documented in kernel manpages (in a single unreadable one >> than is linked ad nauseum). > > cpuset.h is used in userland for cpuset_getaffinity(2), etc. > >> It is otherwise fairly clean. It defines the symbols BITSET_DEFINE, >> BITSET_T_INITIALIZER, and BITSET_SET in the application namespace >> This is not completely clean for a _foo.h header. All other BITSET* >> macros are already in bitset.h I think only BITSET_DEFINE should be >> in _bitset.h (for use declarations in other headers). >> >> select.h avoids this problem by defining its own howmany() macro. This >> seems to be correct except for the bogus ifdef around the private macro. >> This ifdef is a little more than a style bug (verboseness) -- it breaks >> detection of other definitions that might be different. Lexical >> differences wouldn't matter, but it is easier to never have them. >> >> Old versions of select polluted <sys.types.h>. The select macros just >> used howmany(). howmany() was in <sys/types.h> too. > > I would be happy to fix _bitset.h and _cpuset.h to not need sys/param.h. > However, they also use NBBY which is defined in sys/param.h. _sigset.h > gets around this because it uses an array of uint32_t and hardcodes a > shift count of 5 in _SIG_WORD() and a mask of 31 in _SIG_BIT(). If you > think it is fine to hardcode '8' instead of 'NBBY' I'll do that. Hmm, > sys/select.h hardcodes '8' for _NFDBITS, so I guess that is fine. NBBY can be cleaned up too. I rather like it, but it is bogus in C90 since it is spelled CHAR_BIT there, and it is now more bogus in POSIX since POSIX started specifying 8-bit bytes in 2001. Thus 8 is the correct spelling of it in the implementation where you don't want to expose a macro that makes it clearer what this magic 8 is. BTW, I don't like select's and bitset's use of longs. Using unsigned for select is a historical mistake. Bitset apparently copied select except it unimproved to signed long. Bitstring uses unsigned char with no optimizations. Sigset uses uint32_t with no obvious optimizations, but compilers do a good job with with it due to its fixed size. I doubt that the manual optimization of using a wider size is important. Bruce
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