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Date:      Wed, 27 Feb 2002 13:27:48 -0800 (PST)
From:      Julian Elischer <julian@elischer.org>
To:        FreeBSD current users <current@FreeBSD.ORG>
Subject:   controversial fix or some errors breaking LINT
Message-ID:  <Pine.BSF.4.21.0202271318350.97278-100000@InterJet.elischer.org>

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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.

the problem is that it uses "bcopy()" to do this,
and that generates teh error message 
../../../dev/ie/if_ie.c:1232: warning: passing arg 1 of `bcopy' discards
qualifiers from pointer target type
../../../dev/ie/if_ie.c:1232: warning: passing arg 2 of `bcopy' discards
qualifiers from pointer target type


which is now fatal.

Now since it is also possible to copy data INTO a volatile shared buffer
it seems logical to allow bcopy to do so.

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));


NOW we can get rid of lots of UGLY casting tricks here and there that
have been used to try UNVOLATILE things so thay they can use bcopy.
I suggest a similar addition to a few other standard operations.

Hopefully the BUS-space stuff should be used eventually
but I'm not going to rewrite if_ie.c..... are you?
(I've also seem this used in the IPV6 code but I think
thye've been (yukky) cast'ed by now.

julian



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