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Diff for /src/share/lkm/Attic/README between version 1.4 and 1.5

version 1.4, 2003/03/06 04:19:45 version 1.5, 2003/07/09 07:44:29
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 4.0     Loadable module types supported  4.0     Loadable module types supported
   
         There are 6 loadable modules types supported; 5 of these are          There are six loadable modules types supported; five of these are
         specific module types; the sixth is to allow the user to make          specific module types; the sixth is to allow the user to make
         their own loader as part of the module and allow them to replace          their own loader as part of the module and allow them to replace
         or extend apropriate tables in the kernel.          or extend appropriate tables in the kernel.
   
   
 4.1     System call modules  4.1     System call modules
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         If the system call slot is specified, it will replace that          If the system call slot is specified, it will replace that
         specific call (assuming it is in range of the entries in the          specific call (assuming it is in range of the entries in the
         sysent[] table).  Care should be taken when replacing system          sysent[] table).  Care should be taken when replacing system
         calls.  Good candiates are calls which the user is attempting          calls.  Good candidates are calls that the user is attempting
         to repair or make POSIX compliant.  It is possible to replace          to repair or make POSIX compliant.  It is possible to replace
         all calls, although care should be taken with the "ioctl()"          all calls, although care should be taken with the "ioctl()"
         call, as it is the interface for the lkm loader.          call, as it is the interface for the lkm loader.
   
         When unloaded, the system call module replaces the previous          When unloaded, the system call module replaces the previous
         contents of the call slot it was loaded in.  If this was an          contents of the call slot.  If this was an allocable slot, it
         allocable slot, it is now reallocable; if it was a particular          is now reallocable; if it was a particular call slot, the
         call slot, the previous function is restored.          previous function is restored.
   
         The directory ./sample/syscall contains a sample implementation          The directory ./sample/syscall contains a sample implementation
         of a loadable system call.          of a loadable system call.
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         means that there are changes to vfssw[] and mount coming          means that there are changes to vfssw[] and mount coming
         down the road (which will end up incrementing the lkm version          down the road (which will end up incrementing the lkm version
         and introducing an incompatibility as far as file system modules          and introducing an incompatibility as far as file system modules
         are converned).          are concerned).
   
         The directory ./sample/vfs contains the sample implementation          The directory ./sample/vfs contains the sample implementation
         of the loadable kernfs vfs.          of the loadable kernfs vfs.
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 4.3     Device driver modules  4.3     Device driver modules
   
         The major issue to deal with when creating device drivers is          The major issue to deal with when creating device drivers is
         insuring the creation of the device node.  The current approach          ensuring the creation of the device node.  The current approach
         to this is executing a module specific shell script upon a          to this is executing a module specific shell script upon a
         successful load.          successful load.
   
         A potentially better soloution is encoding the device name in          A potentially better solution is encoding the device name in
         the device switch, or, better, providing a functional interface          the device switch, or, better, providing a functional interface
         to the init routine, and then using a "/devices" file system          to the init routine, and then using a "/devices" file system
         to export devices to the file system name space.  Of course,          to export devices to the file system name space.  Of course,
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 4.4     Streams modules  4.4     Streams modules
   
         Streams module support has been removed from this release; when          Streams module support has been removed from this release; when
         the streams implementation is ready, it wil be restored as a          the streams implementation is ready, it will be restored as a
         patch.          patch.
   
         Please do not ask me for early availability on my streams          Please do not ask me for early availability on my streams
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         Execution interpreters allow loading of programs with magic          Execution interpreters allow loading of programs with magic
         numbers other than the default numbers supported by NetBSD.          numbers other than the default numbers supported by NetBSD.
         The reasoning behind this is to effectively allow user space          This allows user space development of changes in exec format
         development of changes in exec format to support, among          to support, among other things, shared libraries.
         other things, shared libraries.  
   
         Another portential use requires changing the references to          Another potential use requires changing the references to
         the "sysent[]" system call table from direct references to          the "sysent[]" system call table from direct references to
         indirect through a pointer in the proc struct.  This allows          indirect through a pointer in the proc struct.  This allows
         the execution interpreter to, among other things, support          the execution interpreter to, among other things, support
         (statically linked) executables from other environments,          (statically linked) executables from other environments,
         like Xenix, SVR3, SVR4, and Linux.          like XENIX, SVR3, SVR4, and Linux.
   
         There is no example of a loadable execution interpreter          There is no example of a loadable execution interpreter
         provided with this distribution.          provided with this distribution.
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 4.6     Miscellaneous modules  4.6     Miscellaneous modules
   
         Miscellaneous modules are modules for which there is not a          Miscellaneous modules are modules for which there is not a
         current, well defined, or well used interface for extension.          current, well-defined, or well-used interface for extension.
         They are provided for extension, and the user is expected to          They are provided for extension, and the user is expected to
         write their own loader to handle the kernel pointer/table          write their own loader to handle the kernel pointer/table
         manipulation to "wire in" their loaded module (and "unwire"          manipulation to "wire in" their loaded module (and "unwire"
         it on uload).          it on unload).
   
         One example of a "miscellaneous module" might be a loader for          One example of a "miscellaneous module" might be a loader for
         card-specific VGA drivers or alternate terminal emualtions in          card-specific VGA drivers or alternate terminal emulations in
         an appropriately layered console driver.          an appropriately layered console driver.
   
         The table manipulations required are specific to the console          The table manipulations required are specific to the console
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