Date: Wed, 27 Feb 2002 18:01:40 -0500 From: Garance A Drosihn <drosih@rpi.edu> To: Julian Elischer <julian@elischer.org>, FreeBSD current users <current@FreeBSD.ORG> Subject: Re: controversial fix or some errors breaking LINT Message-ID: <p05101410b8a31356bb54@[128.113.24.47]> In-Reply-To: <Pine.BSF.4.21.0202271318350.97278-100000@InterJet.elischer.org> References: <Pine.BSF.4.21.0202271318350.97278-100000@InterJet.elischer.org>
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At 1:27 PM -0800 2/27/02, Julian Elischer wrote: >There are saveral places (e.g. if_ie.c) where data >is copied out of a buffer that is shared with the hardware. > >The pointer to this is correctly labelled as "volatile", though >at the time we will copy the data out we know it to be stable. Note: "at the time we will copy the data ... we know" >A while ago I proposed the following patch: > >/* > * Note: the "volatile" below does not REQUIRE that the argument be > * volatile, but rather ony says that it is OK to use a volatile * i > * there. Same for the const. I know a const volatile sounds strange > * but it only indicates that either is acceptable. > */ >void bcopy __P((volatile const void *from, volatile void *to, > size_t len)); This will always allow bcopy to do the copy to or from any volatile location, even if the call is done at a bad time. Any programmer calling bcopy should at least get a little flag waved at them if they are working with volatile arguments. How philosophically sickening would it be to create a macro: #define bcopy_volatile(x,y) bcopy((casts)x,(casts)y) so that you can have cleaner-looking source code, but still have it so the programmer has to *explicitly* say "Yes, I know I am dealing with volatile memory here". -- Garance Alistair Drosehn = gad@eclipse.acs.rpi.edu Senior Systems Programmer or gad@freebsd.org Rensselaer Polytechnic Institute or drosih@rpi.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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