Subject: Re: pg_preadv() and pg_pwritev()
To: Thomas Munro <thomas.munro@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
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From: Sergey Shinderuk <s.shinderuk@postgrespro.ru>
Message-ID: <ed3b8e5d-0da8-6ebd-fd1c-e0ac80a4b204@postgrespro.ru>
Date: Wed, 13 Jan 2021 12:40:06 +0300
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On 11.01.2021 05:59, Thomas Munro wrote:
> Since only sifaka has managed to return a result so far (nice CPU), I
> had plenty of time to notice that macOS Big Sur has introduced
> preadv/pwritev.  They were missing on Catalina[1].
> 
> [1] https://cirrus-ci.com/task/6002157537198080

Hi, Thomas!

Indeed, pwritev is not available on macOS Catalina. So I get compiler 
warnings about that:

/Users/shinderuk/src/pgwork/devel/build/../src/port/pwrite.c:117:10: 
warning: 'pwritev' is only available on macOS 11.0 or newer 
[-Wunguarded-availability-new]
                 part = pg_pwritev(fd, iov, iovcnt, offset);
                        ^~~~~~~~~~
/Users/shinderuk/src/pgwork/devel/build/../src/include/port/pg_iovec.h:49:20: 
note: expanded from macro 'pg_pwritev'
#define pg_pwritev pwritev
                    ^~~~~~~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk/usr/include/sys/uio.h:104:9: 
note: 'pwritev' has been marked as being introduced in macOS 11.0 here, 
but the deployment target is macOS
       10.15.0
ssize_t pwritev(int, const struct iovec *, int, off_t) 
__DARWIN_NOCANCEL(pwritev) __API_AVAILABLE(macos(11.0), ios(14.0), 
watchos(7.0), tvos(14.0));
         ^
/Users/shinderuk/src/pgwork/devel/build/../src/port/pwrite.c:117:10: 
note: enclose 'pwritev' in a __builtin_available check to silence this 
warning
                 part = pg_pwritev(fd, iov, iovcnt, offset);
                        ^~~~~~~~~~
/Users/shinderuk/src/pgwork/devel/build/../src/include/port/pg_iovec.h:49:20: 
note: expanded from macro 'pg_pwritev'
#define pg_pwritev pwritev
                    ^~~~~~~
1 warning generated.
(... several more warnings ...)


And initdb fails:

running bootstrap script ... dyld: lazy symbol binding failed: Symbol 
not found: _pwritev
   Referenced from: /Users/shinderuk/src/pgwork/devel/install/bin/postgres
   Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: _pwritev
   Referenced from: /Users/shinderuk/src/pgwork/devel/install/bin/postgres
   Expected in: /usr/lib/libSystem.B.dylib


Regards.

-- 
Sergey Shinderuk
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company