Date: Sun, 6 Nov 2011 23:50:41 -0500 From: Arnaud Lacombe <lacombar@gmail.com> To: Kostik Belousov <kostikbel@gmail.com> Cc: mdf@freebsd.org, "K. Macy" <kmacy@freebsd.org>, Alan Cox <alc@rice.edu>, Andriy Gapon <avg@freebsd.org>, freebsd-current@freebsd.org, Benjamin Kaduk <kaduk@mit.edu>, Penta Upa <bsdboot@gmail.com> Subject: Re: vm_page_t related KBI [Was: Re: panic at vm_page_wire with FreeBSD 9.0 Beta 3] Message-ID: <CACqU3MUYsyZ8on22cO%2B_6LgK8m2muAE11H%2BNuv0-tqzbvsOVWw@mail.gmail.com> In-Reply-To: <20111106164204.GY50300@deviant.kiev.zoral.com.ua> References: <4EB40015.5040100@rice.edu> <20111104153004.GK50300@deviant.kiev.zoral.com.ua> <4EB4095D.3030303@rice.edu> <20111104160339.GM50300@deviant.kiev.zoral.com.ua> <20111105141306.GW50300@deviant.kiev.zoral.com.ua> <CAMBSHm86TaJnRRgmPA_t7tiPfQsPyoTqz3ymdHSY1H3t5G864Q@mail.gmail.com> <20111105151530.GX50300@deviant.kiev.zoral.com.ua> <4EB595FA.4020500@rice.edu> <20111106124331.GP50300@deviant.kiev.zoral.com.ua> <CAMBSHm-Egy53818aKTpiPBA22RxqTAyQv0q8PsFUnPPDjt1cBQ@mail.gmail.com> <20111106164204.GY50300@deviant.kiev.zoral.com.ua>
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Hi, On Sun, Nov 6, 2011 at 11:42 AM, Kostik Belousov <kostikbel@gmail.com> wrot= e: > On Sun, Nov 06, 2011 at 07:22:51AM -0800, mdf@freebsd.org wrote: >> On Sun, Nov 6, 2011 at 4:43 AM, Kostik Belousov <kostikbel@gmail.com> wr= ote: >> > Regarding the _vm_page_lock() vs. vm_page_lock_func(), the mutex.h has >> > a lot of violations in regard of the namespaces, IMO. The __* namespac= e >> > is reserved for the language implementation, so our freestanding progr= am >> > (kernel) ignores the requirements of the C standard with the names lik= e >> > __mtx_lock_spin(). Using the name _vm_page_lock() is valid, but makes >> > it not unreasonable for other developers to introduce reserved names. >> > So I decided to use the suffixes. vm_map.h locking is free of these >> > violations. >> >> I'm pretty sure that when the C standard says, "the implementation", >> they're referring to the compiler and OS it runs on. =A0Which makes the >> FreeBSD kernel part of "the implementation", which is precisely why so >> many headers have defines that start with __ and then, if certain >> posix defines are set, also uses non-__ versions of the name. > > For libc providing parts, required by standard, you are right. > But our kernel is a freestanding program using a compiler, so in-kernel > uses of the reserved namespace is a violation. > So you prefer to introduce a new notation which will confuses everybody for the sake of following an interpretation of the standard[0] ? Btw, which point of the standard are you quoting ? Section "7.1.3 Reserved identifiers" of ISO/IEC 9899 ? Thanks, - Arnaud ps: my vote is for a deep-sky-blue bikeshed. [0]: I'd be tempted to interpret "the implementation" as the non-visible part of an API, ie vm_page_lock() is public and rely on __vm_page_lock() for its implementation. As such, I would not consider "the kernel" as a single whole unit, but as a sum of public API and implementation.
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