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Date: Mon, 18 Jun 2001 08:59:11 -0700 (PDT)
From: Robert Cousins <rec@RCousins.com>
To: freebsd-gnats-submit@FreeBSD.org
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Subject: kern/28260: UIO_MAXIOV needs to be made public
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>Number:         28260
>Category:       kern
>Synopsis:       UIO_MAXIOV needs to be made public
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Jun 18 09:00:14 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Robert Cousins
>Release:        3.2
>Organization:
Cousins Consulting
>Environment:
FreeBSD www0.RCousins.com 3.2-RELEASE FreeBSD 3.2-RELEASE #3: Sat Jul 31 09:43:05 PDT 1999     root@aim-0.RCousins.com:/usr/src/sys/compile/REC_1  i386

>Description:
When I use writev() or readv(), I found that I got an error when the
iovec was more than 1024 long. I checked and the proper limits value
is UIO_MAXIOV. However, while this is in /usr/include/sys/uio.h, it
is behind a #ifdef KERNEL which means that "normal" code won't be
able to see it.

I don't know about any applicable standards where there is an equivalent
limit. (Solaris has a much more stringent restriction of 16 if memory
serves. However, I sometimes use 2000 or more entries to a writev().)
>How-To-Repeat:

>Fix:
Suggested fix:
1. Move UIO_MAXIOV above the #ifdef KERNEL in uio.h 
- or -
2. Change to use a standard value (whatever it might be, I don't know).
>Release-Note:
>Audit-Trail:
>Unformatted:

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