Rebuild all network-related kernel modules on 8-current due to vnet allocator change

Robert Watson rwatson at
Tue Jul 14 23:20:19 UTC 2009

Just a quick heads up:

The attached change, which just entered 8-current, modifies kernel programming 
and binary interfaces for many network stack components/modules.  You will 
want to make sure all kernel modules are rebuilt.

For those willing to take a risk, here's a list of the kernel modules (and of 
course the kernel) that I know are definitely affected and will want to be 

bridgestp.ko	if_vlan.ko	kernel		ng_atm.ko	sppp.ko
if_bridge.ko	ip_mroute.ko	linprocfs.ko	ng_eiface.ko	svr4.ko
if_ef.ko	ipdivert.ko	linux.ko	ng_ether.ko	wlan.ko
if_faith.ko	ipfw.ko		netgraph.ko	ng_gif.ko
if_gif.ko	ipfw_nat.ko	nfscl.ko	ng_iface.ko
if_gre.ko	ipl.ko		nfsclient.ko	pf.ko
if_stf.ko	iw_cxgb.ko	nfsd.ko		rdma_cma.ko

(For those interested: I grepped for vnet_entry in my local kernel module 
collection -- these are kernel modules that directly reference virtualized 
global network stack variables with a VIMAGE configuration).

Robert N M Watson
Computer Laboratory
University of Cambridge

---------- Forwarded message ----------
Date: Tue, 14 Jul 2009 22:48:30 +0000 (UTC)
From: Robert Watson <rwatson at>
To: src-committers at, svn-src-all at,
     svn-src-head at
Subject: svn commit: r195699 - in head: . sys/compat/linprocfs sys/compat/linux
     sys/compat/svr4 sys/conf sys/contrib/altq/altq sys/contrib/ipfilter/netinet
     sys/contrib/pf/net sys/contrib/rdma sys/ddb sys/de...

Author: rwatson
Date: Tue Jul 14 22:48:30 2009
New Revision: 195699

   Build on Jeff Roberson's linker-set based dynamic per-CPU allocator
   (DPCPU), as suggested by Peter Wemm, and implement a new per-virtual
   network stack memory allocator.  Modify vnet to use the allocator
   instead of monolithic global container structures (vinet, ...).  This
   change solves many binary compatibility problems associated with
   VIMAGE, and restores ELF symbols for virtualized global variables.

   Each virtualized global variable exists as a "reference copy", and also
   once per virtual network stack.  Virtualized global variables are
   tagged at compile-time, placing the in a special linker set, which is
   loaded into a contiguous region of kernel memory.  Virtualized global
   variables in the base kernel are linked as normal, but those in modules
   are copied and relocated to a reserved portion of the kernel's vnet
   region with the help of a the kernel linker.

   Virtualized global variables exist in per-vnet memory set up when the
   network stack instance is created, and are initialized statically from
   the reference copy.  Run-time access occurs via an accessor macro, which
   converts from the current vnet and requested symbol to a per-vnet
   address.  When "options VIMAGE" is not compiled into the kernel, normal
   global ELF symbols will be used instead and indirection is avoided.

   This change restores static initialization for network stack global
   variables, restores support for non-global symbols and types, eliminates
   the need for many subsystem constructors, eliminates large per-subsystem
   structures that caused many binary compatibility issues both for
   monitoring applications (netstat) and kernel modules, removes the
   per-function INIT_VNET_*() macros throughout the stack, eliminates the
   need for vnet_symmap ksym(2) munging, and eliminates duplicate
   definitions of virtualized globals under VIMAGE_GLOBALS.

   Bump __FreeBSD_version and update UPDATING.

   Portions submitted by:  bz
   Reviewed by:            bz, zec
   Discussed with:         gnn, jamie, jeff, jhb, julian, sam
   Suggested by:           peter
   Approved by:            re (kensmith)

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