Today marks the release of OpenBSD 5.0, the next great release of OpenBSD. This release marks significant improvements in hardware supports and functionality. I have been using my own personal build of OpenBSD 5.0 for several months. It is a great improvement and also features lots of updates in many areas. Especially of interest to me is the inclusion Dovecot 2.0 for the first time in an OpenBSD release.

The new and significant changes are listed on the OpenBSD 5.0 release page. Here are some highlights.

Improved hardware support, including:

MSI interrupts for many devices, on those architectures which can support them (amd64, i386, sparc64 only so far).
A new dma_alloc(9) API makes it easier for kernel code to allocate dma-safe memory. Many drivers (especially network drivers) and subsystems (in particular scsi and the buffer cache) were adapted to use this.
As a result, big-memory support has been enabled on all possible architectures.

Generic network stack improvements:

Added support for sending Wake on Lan packets using arp(8).
Permit turning Wake on Lan support on/off using ifconfig(8).
Added Wake on Lan support to xl(4), re(4), and vr(4).
The IPv4 stack will no longer accept ICMP redirects when acting as a router.
Make gre(4) work between systems in the same LAN.
Kernel randomization speed and quality improved substantially.

pf(4) improvements:

Make pf(4) reassemble IPv6 fragments. In the forward case, pf refragments the packets with the same maximum size.
Allow pf(4) to filter on the rdomain a packet belongs to.
Make pf(4) allow userland proxies to establish cross rdomain proxy sessions.
Added IPv6 ACK prioritization in pf(4).
Change 'set skip on <... data-preserve-html-node="true">' to work with interface groups.
pfsync(4) supports IPv6 as network protocol.
Switched ftp-proxy(8) over to divert-to instead of rdr-to.
tftp-proxy(8) uses 'divert-to' as well.

SCSI improvements:

most SCSI hardware drivers now use the new iopools infrastructure.
scsi(4) devices are now all provided with a unique devid, which is displayed during the probe process.
ASC/ASCQ error codes and verbiage now in sync with http://www.t10.org/lists/asc-num.txt.
progress on iSCSI includes better login, better logout, preliminary FSM support in iscsid(8), and improved logging and debug information.
uk(4) can now safely and reliably detach an unknown SCSI device.
mpath(4) device and kernel support is improved.
vscsi(4) now ensures output always goes to the correct connection.
vscsi(4) connections can now be reset gracefully.
scsi(4) devices on fibre channel fabrics no longer inherit the adapter's address.

Assorted improvements:

For additional security, security(8) was rewritten in Perl.
Mandoc 1.11.4: Now accepts eqn(7) input (no fancy formatting yet) and supports -Tutf8 output (but no utf8 input yet).
Removed a variety of OS-compat emulation code, leaving just the Linux support.
Small improvements to Linux compat (only available on i386).
On MBR-based disks, scan through up to 256 extended partition tables when looking for an OpenBSD partition table.
Improved correctness of signals and various syscalls when rthreads are in use.
Fixed some shutdown/reboot hangs on NFS clients.

Install/Upgrade process changes:

Completed support for DUID disk installs, and enabled it fully.
Tried to make sysmerge(8) work in the installer, but ran into small problems and decided to disable it.
Install non-free firmwares from the internet upon first boot, based on a question in the installer.
svnd(4)-like behaviour became the default for vnd(4) devices. This is what is used to build the media.

rc.d(8) framework improvements:

rc.d(8) is now also used for the base system daemons.
Backward compatible with the historic way of starting daemons.
Notify the user by appending (ok) or (failed) in interactive mode.
Better diagnostics with the introduction of RC_DEBUG.

OpenSSH 5.9

As always, there are also many improvements to packages with each new release. I mentioned the inclusion of Dovecot 2.0 above. The full details are available on the OpenBSD 5.0 release page.