Grepping the source of the pages in man-pages will show various places where pages are marked with the string "FIXME". There is also a shell script (scripts/FIXME_list.sh) that can be used to obtain a list of FIXMEs in the man page sources:
The presence of a FIXME usually indicates that someone has noticed that some information on the page is incorrect or incomplete, but has not had the time/knowledge to fix the problem. (Sometimes a FIXME relates to a kernel or glibc bug report that is awaiting resolution, and it may be sufficient to check if the bug has been resolved and then, if necessary, provide a suitable write-up on the page.)
If you know how to fix the problem, then please send a patch. However, note that some of the FIXME markings are associated with problems that are quite difficult: you need to ensure that you are knowledgeable on the relevant point(s), or you need to be willing to invest the time to become knowledgeable (by reading kernel or [g]libc source files and/or writing suitable test programs).
A list of some of the FIXMEs that were current as at October 2007 is shown below.
man2/futex.2
FIXME
2.6.18 adds (Ingo Molnar) priority inheritance support:
FUTEX_LOCK_PI, FUTEX_UNLOCK_PI, and FUTEX_TRYLOCK_PI. These need
to be documented in the manual page. Probably there is sufficient
material in the kernel source file Documentation/pi-futex.txt.
man2/ioperm.2
FIXME is the following ("Only the first 0x3ff I/O ports can be
specified in this manner") still true? Looking at changes in
include/asm-i386/processor.h between 2.4 and 2.6 suggests
that the limit is different in 2.6.
man2/mount.2
FIXME 2.6.15 added flags for "shared sub-tree" functionality:
MS_UNBINDABLE, MS_PRIVATE, MS_SHARED, MS_SLAVE
These need to be documented on this page.
See Documentation/sharedsubtree.txt
FIXME Say more about MS_MOVE
FIXME Document MS_REC, available since 2.4.11.
This flag has meaning in conjunction with MS_BIND and
also with the shared sub-tree flags.
FIXME Can MNT_FORCE result in data loss? According to
the Solaris manual page it can cause data loss on Solaris.
If the same holds on Linux, then this should be documented.
man2/mprotect.2
FIXME
Document PROT_GROWSUP and PROT_GROWSDOWN
man2/nfsservctl.2
FIXME The description of nfsservctl() on this page
is woefully thin.
man2/quotactl.2
FIXME There is much that is missing and/or out of date in this page.
As things stand the page more or less documents Linux 2.2 reality:
Linux 2.2 has:
Q_GETQUOTA
Q_GETSTATS
Q_QUOTAOFF
Q_QUOTAON
Q_RSQUASH (not currently documented)
Q_SETQLIM
Q_SETQUOTA
Q_SETUSE
Q_SYNC
Linux 2.4 has:
Q_COMP_QUOTAOFF
Q_COMP_QUOTAON
Q_COMP_SYNC
Q_GETFMT
Q_GETINFO
Q_GETQUOTA
Q_QUOTAOFF
Q_QUOTAON
Q_SETINFO
Q_SETQUOTA
Q_SYNC
Q_V1_GETQUOTA Q_V1_GETSTATS Q_V1_RSQUASH Q_V1_SETQLIM
Q_V1_SETQUOTA Q_V1_SETUSE
Q_V2_GETINFO Q_V2_GETQUOTA Q_V2_SETFLAGS Q_V2_SETGRACE
Q_V2_SETINFO Q_V2_SETQUOTA Q_V2_SETUSE
Q_XGETQSTAT Q_XGETQUOTA Q_XQUOTAOFF Q_XQUOTAON Q_XQUOTARM
Q_XSETQLIM
Linux 2.6.16 has:
Q_GETFMT
Q_GETINFO
Q_GETQUOTA
Q_QUOTAOFF
Q_QUOTAON
Q_SETINFO
Q_SETQUOTA
Q_SYNC
Q_XGETQSTAT
Q_XGETQUOTA
Q_XQUOTAOFF
Q_XQUOTAON
Q_XQUOTARM
Q_XQUOTASYNC
Q_XSETQLIM
man2/shmop.2
FIXME A good explanation of the rationale for the existence
of SHMLBA would be useful here
FIXME That last sentence isn't true for all Linux
architectures (i.e., SHMLBA != PAGE_SIZE for some architectures)
-- MTK, Nov 04
man3/confstr.3
FIXME Many more values for 'name' are supported, some of which
are documented under 'info confstr'.
See for the rest.
These should all be added to this page.
See also the POSIX.1-2001 specification of confstr()
man3/fopen.3
FIXME document /,ccs= charset/
man3/getaddrinfo.3
FIXME glibc defines the following additional errors, some which
can probably be returned by getaddrinfo(); they need to
be documented.
# ifdef __USE_GNU
# define EAI_INPROGRESS -100 /* Processing request in progress. */
# define EAI_CANCELED -101 /* Request canceled. */
# define EAI_NOTCANCELED -102 /* Request not canceled. */
# define EAI_ALLDONE -103 /* All requests done. */
# define EAI_INTR -104 /* Interrupted by a signal. */
# define EAI_IDN_ENCODE -105 /* IDN encoding failed. */
# endif
man3/getnameinfo.3
FIXME glibc defines the following additional errors, some which
can probably be returned by getnameinfo(); they need to
be documented.
# ifdef __USE_GNU
# define EAI_INPROGRESS -100 /* Processing request in progress. */
# define EAI_CANCELED -101 /* Request canceled. */
# define EAI_NOTCANCELED -102 /* Request not canceled. */
# define EAI_ALLDONE -103 /* All requests done. */
# define EAI_INTR -104 /* Interrupted by a signal. */
# define EAI_IDN_ENCODE -105 /* IDN encoding failed. */
# endif
man5/locale.5
FIXME glibc 2.2.2 added new non-standard locale categories:
LC_ADDRESS, LC_IDENTIFICATION, LC_MEASUREMENT, LC_NAME,
LC_PAPER, LC_TELEPHONE. These need to be documented.
man5/proc.5
FIXME 2.6.13 seems to have /proc/vmcore implemented
in the source code, but there is no option available under
'make xconfig'; eventually this should be fixed, and then info
from the patch-2.6.13 and change log could be used to write an
entry in this man page.
FIXME cross check against Documentation/filesystems/proc.txt
to see what information could be imported from that file
into this file.
FIXME Describe /proc/[number]/loginuid
Added in 2.6.11; updating requires CAP_AUDIT_CONTROL
FIXME Describe /proc/[number]/mountstats and
/proc/PID/task/TID/mountstats
Some information can be found in the 2.6.17-rc1 change log.
Added in 2.6.17
FIXME Describe /proc/[number]/seccomp
Added in 2.6.12
FIXME Actually, the following info about the /proc/stat 'cpu' field
does not seem to be quite right (at least in 2.6.12)
FIXME The following is not the full picture for the 'intr' of
/proc/stat on 2.6:
FIXME more should be said about /proc/zoneinfo
man7/capabilities.7
FIXME CAP_KILL also has an effect for threads + setting child
termination signal to other than SIGCHLD: without this
capability, the termination signal reverts to SIGCHLD
if the child does an exec(). What is the rationale
for this?
FIXME CAP_SETUID also an effect in exec(); document this.
FIXME CAP_SYS_NICE also has the following effect for
migrate_pages(2):
do_migrate_pages(mm, &old, &new,
capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
man7/ipv6.7
FIXME IPV6_CHECKSUM is not documented, and probably should be
FIXME IPV6_JOIN_ANYCAST is not documented, and probably should be
FIXME IPV6_LEAVE_ANYCAST is not documented, and probably should be
FIXME IPV6_V6ONLY is not documented, and probably should be
FIXME IPV6_RECVPKTINFO is not documented, and probably should be
FIXME IPV6_2292PKTINFO is not documented, and probably should be
FIXME there are probably many other IPV6_* socket options that
should be documented
man7/locale.7
FIXME glibc 2.2.2 added new non-standard locale categories:
LC_ADDRESS, LC_IDENTIFICATION, LC_MEASUREMENT, LC_NAME,
LC_PAPER, LC_TELEPHONE. These need to be documented.
man7/netlink.7
FIXME More details on NETLINK_INET_DIAG needed.
FIXME More details on NETLINK_XFRM needed.
FIXME More details on NETLINK_ISCSI needed.
FIXME More details on NETLINK_AUDIT needed.
FIXME More details on NETLINK_FIB_LOOKUP needed.
FIXME More details on NETLINK_NETFILTER needed.
FIXME More details on NETLINK_KOBJECT_UEVENT needed.
FIXME NLM_F_ATOMIC is not used any more?
FIXME Explain more about nlmsg_seq and nlmsg_pid.
man7/tcp.7
FIXME 2.6.17-rc1 adds the following /proc files, which need to be
documented: tcp_mtu_probing, tcp_base_mss, and
tcp_workaround_signed_windows
FIXME As at Sept 2006, kernel 2.6.18-rc5, the following are
not yet documented (shown with default values):
/proc/sys/net/ipv4/tcp_congestion_control (since 2.6.13)
bic
/proc/sys/net/ipv4/tcp_moderate_rcvbuf
1
/proc/sys/net/ipv4/tcp_no_metrics_save
0
FIXME Document TCP_CONGESTION (new in 2.6.13)
man7/udp.7
FIXME document UDP_ENCAP (new in kernel 2.5.67)