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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/highuid.txt | |
download | kernel_samsung_crespo-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip kernel_samsung_crespo-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz kernel_samsung_crespo-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.bz2 |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/highuid.txt')
-rw-r--r-- | Documentation/highuid.txt | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/Documentation/highuid.txt b/Documentation/highuid.txt new file mode 100644 index 0000000..2c33926 --- /dev/null +++ b/Documentation/highuid.txt @@ -0,0 +1,79 @@ +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 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 space 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 + 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 use 32-bit UIDs in + all ioctl()s. Some new ioctl()s have been added with 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) + + +Chris Wing +wingc@umich.edu + +last updated: January 11, 2000 |