DragonFly BSD 是一套开放原始码的类 Unix 作业系统，自 FreeBSD 4.8 分支。
由于 FreeBSD 开发组将于 FreeBSD 4.11 后不再推出新的 4 系列版本（仅做安全性更新），而新的 FreeBSD 5 系列初期又有效能及稳定性等等的质疑，因此 Matt Dillon 在 2003年六月 另外成立分支计划，并于同年七月时于 FreeBSD 的邮件讨论群组上公布。
Dillon 当时认为 FreeBSD 5 所使用的 Threading 与 SMP 架构将会使得系统难以维护，但不被 FreeBSD 的发展团队接受，于是决定自行发展分支。即便如此，DragonFly BSD 的发展团队仍与 FreeBSD 密切合作，双方仍然经常互相帮助对方修正臭虫，以及驱动程式的更新。
DragonFly BSD 2.10发行说明如下：
Kernel changes
Update of pf from OpenBSD 4.2 to 4.4, keeping DragonFly specific additions (support for pickups and fairq). mlockall(2)/munlockall(2) implemented devfs chown/chmod bug fixes Major overhaul of the device mapper (dm) dm_target_crypt now uses mpipe for memory allocations New kern.proc.cwd sysctl Major overhaul of the vn(4) driver Many sysctls now have a description msdosfs bug fixes mbuf now supports MJUMPAGESIZE Fix fstatfs() and fstatvfs() when called from a null-mounted chroot() Several subsystems switched from zalloc to objcache (ufs dirhash, NFS, aio, crypto) Minimum UNDO storage raised to 500M by newfs_hammer. Lots of code WARNS raises to improve portability. ACPI interrupt routing implemented and enabled by default ACPI - tons of work has gone into our ACPI support. APIC_IO now acts as a default and can be changed in /boot/loader.conf Overhaul LWKT and USCHED schedulers for MP performance when many cpus are present. Significant HAMMER bug fixes and performance improvements. HAMMER enhancements to allow swapcache to more easily cache file data via vfs.hammer.double_buffer mode. HAMMER double_buffer mode's strategy code is now asynchronous. CAM tag reservation code fixed for AHCI and SILI drivers. CAM DA driver enhanced to separate read and write streams, allowing concurrent write completion in the face of many stalled read requests. Major enhancements to the if_bridge code, adding support for bonding, weights, and other features. Use blocking mbufs in TAP/TUN to avoid unnecessary packet loss. Fixed a few difficult-to-reproduce bugs in the VM system Major timer functionality changes, the 8254 will no longer be used unless there is no other choice. Jump page support added to the mbuf API and used in several WIFI drivers. Fix bugs in ktrace related to the MP work which could freeze the system. LWKT thread migration code redone. The FAIRQ altq has been significantly enhanced and now supports weighted expansion of bandw
idths up to the interface bandwidth. Lots of MP-related bug fixes to the network stack. Use MONITOR/MWAIT in the idle thread as an intermediate step prior to ACPI halt.
Hardware changes (non-networking)
mfi(4) RAID driver and mfiutil(8) configuration tool added. arcmsr(4) updated twe(4) updated amr(4) updated aac(4) updated hptmv(4) added hptiop(4) added dc(4) support for the Abocom FE
2500 tws(4) added, a driver for the LSI 3ware 9750 series SATA/SAS RAID controllers. aesni(4) bug fixes kqueue added to ulpt to improve CUPS support. AHCI driver enhanced to better support semi-broken chipsets which do not properly mask transient phy events during training. AHCI driver hotplug support improved.
Hardware changes (networking)
Wireless cards utilizing the following drivers are supported in this release: ath, iwi, iwn, ral, wi, wpi. (update me) The following drivers have not been ported and will not yet work: acx, an, bwi, ndis, rtw, rum, ural. (update me)
New Multiprocessor Safe Work
BGL replaced by mp_token, mp_token replaced by per-subsystem tokens in nearly all cases Most per-subsystem tokens replaced with fine-grained tokens, except for VM. The lwkt_token API has been greatly simplified. Numerous scheduler and memory management changes to improve MP performance.
Userland changes
The installer now allows you to crypt swap and root libcrypt now supports sha256/512 The default password hash is now sha256 dmsetup now supports remove_all utmpx and wtmpx support newfs now supports volume names hammer(8) now supports listing volumes New library libfsid, used to determine what FS is on a given volume New utility: devattr, exposes the libdevattr and kern_udev functionality fstat(1) now supports devfs powerd now dynamically reduces the set of cpus available and adjusts their frequencies independently when the hardware supports it. GLOB_LIMIT removed from ftpd because it was getting hit by nominal pkgsrc operations. Swapcache removes most of the DOS attack potential.
x86_64-specific changes
64-bit systems now can support up to 63 CPUs and 5
12G of RAM Much faster early-kernel-boot memory test More generous kernel resource limits
Removals
TBD
Contributed Software
Shipping with pkgsrc-2011
Q1 built packages. Code from DragonFly's participation in Google Code-In 2011 Updated ldns/drill to 1.6.7 Updated libarchive to 2.8.4 Updated zlib to 1.2.5 Updated
OpenSSL to 1.0.0d Updated OpenSSH to -5.8p1 Updated file to 5.05 Updated zoneinfo to tzdata2011g Updated binutils to 2.21 Updated acpica to 20110211 Updated mdocml to 1.10.9 Updated gcc to 4.4.5 Imported xz-5.0.0 Imported binutils 2.21
Security related
A security issue in OpenSSL (CVE-2011-0014) was fixed.
下载地址：
dfly-i386-2.10.1_REL.iso.bz2 (185MB)
dfly-x86_64-2.10.1_REL.iso.bz2 (190MB).