From owner-freebsd-hackers  Mon Oct 16 15: 0:21 2000
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Date: Mon, 16 Oct 2000 15:00:17 -0700
From: Alfred Perlstein <bright@wintelcom.net>
To: hackers@freebsd.org
Cc: bde@freebsd.org
Subject: readv manpage != UIO_MAXIOV
Message-ID: <20001016150017.T272@fw.wintelcom.net>
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Several months ago I was having trouble porting a program of mine
to solaris, the problem was that I'd get EINVAL back from writev/readv
if my iovec was larger than 16 entries long.

I thought this was a pretty stupidly set low limit, however the
solaris #define for it looked pretty official:

sys/socket.h:#define    MSG_MAXIOVLEN   16
sys/stream.h:#define    DEF_IOV_MAX     16

anyhow, I just noticed that our manpages now proclaim a 16 entry
limit, however our kernel code doesn't seemt to mind up to 1024
iovs.  (sys/uio.h:#define UIO_MAXIOV    1024)

So do we:
a) change the kernel to match the docco and possibly breaks
   lotsa stuff?
b) change the docco to note that although FreeBSD allows 
   more than 16 iovecs, it's not recommeneded for portability
   reasons
c) change readv/writev but provide compat syscalls.


-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."


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