[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 1 of 5] blktap: remove HAVE_BYTESWAP_H checking, since it's defined by qemu
Hi, On Mon, Dec 19, 2011 at 3:48 AM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote: > On Sun, 2011-12-18 at 12:48 +0000, Roger Pau Monne wrote: >> # HG changeset patch >> # User Roger Pau Monne <roger.pau@xxxxxxxxxxxxx> >> # Date 1324171782 -3600 >> # Node ID eed78eb655c40b0ac9af1b14c1cc03204f696b0b >> # Parent b783e76e63a99c9d87fca4974492f60af99a2e7a >> blktap: remove HAVE_BYTESWAP_H checking, since it's defined by qemu >> >> blktap was using defines set by qemu, even when the qemu config file >> is not included. Remove this checkings, and instead check if the file >> has been included before defining the necessary macros. >> >> The output error is: >> >> In file included from block-qcow.c:37:0: >> bswap.h:23:0: error: "bswap_16" redefined [-Werror] >> /usr/include/byteswap.h:30:0: note: this is the location of the >> previous definition >> bswap.h:31:0: error: "bswap_32" redefined [-Werror] >> /usr/include/byteswap.h:33:0: note: this is the location of the >> previous definition >> bswap.h:41:0: error: "bswap_64" redefined [-Werror] >> /usr/include/byteswap.h:37:0: note: this is the location of the >> previous definition >> cc1: all warnings being treated as errors >> >> Signed-off-by: Roger Pau Monne <roger.pau@xxxxxxxxxxxxx> >> >> diff -r b783e76e63a9 -r eed78eb655c4 tools/blktap/drivers/bswap.h >> --- a/tools/blktap/drivers/bswap.h Sun Dec 18 02:29:42 2011 +0100 >> +++ b/tools/blktap/drivers/bswap.h Sun Dec 18 02:29:42 2011 +0100 >> @@ -15,9 +15,7 @@ >> #define bswap_64(x) swap64(x) >> #else >> >> -#ifdef HAVE_BYTESWAP_H >> -#include <byteswap.h> >> -#else >> +#ifndef _BYTESWAP_H > > This is basically saying "if the user hasn't already include byteswap.h" > but it seems to rely on that header using the precise guard _BYTESWAP_H > which I presume can differ across platforms. I don't think this is a > viable approach. > > Given that we have our own definitions of these things any why not just > remove the ifdef and single the other #include of byteswap.h and always > use the ones we defined? > > The other alternative is to remove our own version and always include > byteswap.h. > > The right answer depends on how standardised byteswap.h is. It seems to > be in glibc but is it in uclibc and the BSD libcs? I can't find a > definitive reference but it seems like it is specified by POSIX? uClibc 0.9.32 and later have byteswap.h. Not sure about earlier versions. byteswap.h is a GNU-ism though, and not in any of the BSDs as a result. We should just ship these definitions directly in Xen and not depend on it. William _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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