From 81020547cb0b0569b6b41fc842b1f2133851cb06 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Sun, 17 Mar 2013 15:10:43 +0100 Subject: [PATCH] mq_overview.7: Update details on defaults and ceiling for 'msgsize_max' limit Signed-off-by: Michael Kerrisk --- man7/mq_overview.7 | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/man7/mq_overview.7 b/man7/mq_overview.7 index 5eff94b07..f8af879b2 100644 --- a/man7/mq_overview.7 +++ b/man7/mq_overview.7 @@ -184,11 +184,20 @@ is 8192 bytes. The minimum value is 128 (8192 in kernels before 2.6.28). The upper limit for .I msgsize_max -is 1,048,576 (in kernels before 2.6.28, the upper limit was +has varied across kernel versions: +before Linux 2.6.28, the upper limit was .BR INT_MAX ; -that is, 2,147,483,647 on Linux/86). -This limit is ignored for privileged processes -.RB ( CAP_SYS_RESOURCE ). +(that is, 2,147,483,647 on Linux/86); +starting with Linux 2.6.38, the limit was 1,048,576; +since Linux 3.5, the limit is 16,777,216 +.RB ( HARD_MSGSIZEMAX ). +The +.I msgsize_max +limit is ignored for privileged process +.RB ( CAP_SYS_RESOURCE ), +but, since Linux 3.5, the +.BR HARD_MSGSIZEMAX +ceiling is enforced for privileged processes. .TP .I /proc/sys/fs/mqueue/queues_max This file can be used to view and change the system-wide limit on the