patch-2.3.39 linux/Documentation/highuid.txt

• Lines: 79
• Date: Mon Jan 10 18:15:58 2000
• Orig file: v2.3.38/linux/Documentation/highuid.txt
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.38/linux/Documentation/highuid.txt linux/Documentation/highuid.txt
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+Notes on the change from 16-bit UIDs to 32-bit UIDs:
+
+- kernel code MUST take into account __kernel_uid_t and __kernel_uid32_t
+  when communicating between user and kernel space in an ioctl or data
+  structure.
+
+- kernel code should use uid_t and gid_t in kernel-private structures and
+  code.
+
+What's left to be done for 32-bit UIDs on all Linux architectures:
+
+- Disk quotas have an interesting limitation that is not related to the
+  maximum UID/GID. They are limited by the maximum file size on the
+  underlying filesystem, because quota records are written at offsets
+  corresponding to the UID in question.
+  Further investigation is needed to see if the quota system can cope
+  properly with huge UIDs. If it can deal with 64-bit file offsets on all 
+  architectures, this should not be a problem.
+
+- Decide on a final layout for the new msqid64_ds, semid64_ds, and
+  shmid64_ds, and shminfo64 structures. The current ones leave pad space
+  for 64-bit time_t and 32-bit pid_t, as well as 4 extra machine words.
+  Perhaps more pad space should be left for future use?
+
+- Decide whether or not to keep backwards compatibility with the system
+  accounting file, or if we should break it as the comments suggest
+  (currently, the old 16-bit UID and GID are still written to disk, and
+  part of the former pad sparce is used to store separate 32-bit UID and
+  GID)
+
+- Need to validate that OS emulation calls the 16-bit UID
+  compatibility syscalls, if the OS being emulated used 16-bit UIDs, or
+  uses the 32-bit UID system calls properly otherwise.
+
+  This affects at least:
+	SunOS emulation - now fixed?
+	Solaris emulation
+	iBCS on Intel
+
+	sparc32 emulation on sparc64
+	(need to support whatever new 32-bit UID system calls are added to
+	sparc32)
+
+- Validate that all filesystems behave properly.
+
+  At present, 32-bit UIDs _should_ work for:
+	ext2
+	ufs
+	isofs
+	nfs
+	coda
+	udf
+
+  Ioctl() fixups have been made for:
+	ncpfs
+	smbfs
+
+  Filesystems with simple fixups to prevent 16-bit UID wraparound:
+	minix
+	sysv
+	qnx4
+
+  Other filesystems have not been checked yet.
+
+- The ncpfs and smpfs filesystems can not presently return 32-bit UIDs to
+  all ioctl()s. Some new ioctl()s have been added for 32-bit UIDs, but
+  more are needed. (as well as new user<->kernel data structures)
+
+- The ELF core dump format only supports 16-bit UIDs on arm, i386, m68k,
+  sh, and sparc32. Fixing this is probably not that important, but would
+  require adding a new ELF section.
+
+- The ioctl()s used to control the in-kernel NFS server only support
+  16-bit UIDs on arm, i386, m68k, sh, and sparc32.
+
+- make sure that the UID mapping feature of AX25 networking works properly
+  (it should be safe because it's always used a 32-bit integer to
+  communicate between user and kernel)