ftp://ftp.swin.edu.au/freebsd/development/FreeBSD-CVS/src/sys/  direct

[DIR]xen/  direct  9014+ twin directories
[DIR]xdr/  direct  666+ twin directories
[DIR]vm/  direct  7868+ twin directories
[DIR]ufs/  direct  4733+ twin directories
[DIR]tools/  direct  48166+ twin directories
[DIR]sys/  direct  32688+ twin directories
[DIR]svr4/  direct  1235+ twin directories
[DIR]sun4v/  direct  245+ twin directories
[DIR]sparc64/  direct  19217+ twin directories
[DIR]security/  direct  23527+ twin directories
[DIR]scsi/  direct  13137+ twin directories
[DIR]rpc/  direct  6260+ twin directories
[DIR]powerpc/  direct  19182+ twin directories
[DIR]posix4/  direct  147 twin directories
[DIR]pci/  direct  23578+ twin directories
[DIR]pccard/  direct  1026+ twin directories
[DIR]pc98/  direct  1981+ twin directories
[DIR]opencrypto/  direct  246+ twin directories
[DIR]nwfs/  direct  373+ twin directories
[DIR]ntfs/  direct  3578+ twin directories
[DIR]nlm/  direct  1175+ twin directories
[DIR]nfsserver/  direct  249+ twin directories
[DIR]nfsclient/  direct  248+ twin directories
[DIR]nfs4client/  direct  186 twin directories
[DIR]nfs/  direct  6928+ twin directories
[DIR]netsmb/  direct  522+ twin directories
[DIR]netns/  direct  499+ twin directories
[DIR]netncp/  direct  130 twin directories
[DIR]netnatm/  direct  435+ twin directories
[DIR]netkey/  direct  342+ twin directories
[DIR]netiso/  direct  289+ twin directories
[DIR]netipx/  direct  375+ twin directories
[DIR]netipsec/  direct  284+ twin directories
[DIR]netinet6/  direct  521+ twin directories
[DIR]netinet/  direct  4356+ twin directories
[DIR]netgraph/  direct  517+ twin directories
[DIR]netccitt/  direct  215+ twin directories
[DIR]netatm/  direct  130 twin directories
[DIR]netatalk/  direct  3313+ twin directories
[DIR]net80211/  direct  517+ twin directories
[DIR]net/  direct  39585+ twin directories
[DIR]msdosfs/  direct  942+ twin directories
[DIR]modules/  direct  65339+ twin directories
[DIR]miscfs/  direct  465+ twin directories
[DIR]mips/  direct  13164+ twin directories
[DIR]libkern/  direct  515+ twin directories
[DIR]kern/  direct  806+ twin directories
[DIR]isofs/  direct  2262+ twin directories
[DIR]isa/  direct  6783+ twin directories
[DIR]ia64/  direct  27596+ twin directories