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Diffstat (limited to 'NOTES')
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@@ -0,0 +1,153 @@ + +Pre-notes + + The cutting of the channel system is not as clean as I would like + it to be, simply because cisco has the special need of a channel + system trimmed down to the std* channels, without complete removal. + I am not sure that I have removed the maximum amount of C Api's + and functions possible for this specific configuration. + + A first step in rationalizing this section would be NO_CHANNELS + to remove the I/O system completely, and then NO_NONSTDCHAN + for minial exposure of channels. NO_FILEEVENTS is orthogonal + to NO_NONSTDCHAN. Drivers are possible only if not NO_CHANNELS, + but can be disabled separately. The standard channels need the + "file" driver (currently not disable-able), should use #ifdef's + to ensure integrity. + + => Would be interesting to have a configuration tool which + is able to express and enforce these constraints. + + => The linux core configuration uses the domain specific + language CML2 (Eric Raymond, written in Python). + + ! Investigate possible usage of SourceNavigator as + basic for parsing the Tcl core. Use custom tools to + follow dependencies between structures and functions. + + (What-If tools: What if I exclude this function/struct, + what else can be removed, or requires this). + + Also: What are the leaf functions in the system ... + + ! Mapping help: Associate functions with functional areas + and see how the areas relate, how much can be removed + whenever an area is excluded ... + +------------------------------------------------------------------------ +------------------------------------------------------------------------ +------------------------------------------------------------------------ + +Shrinking the core. + Filesystem + +Shrinking the usage of stack + Large static arrays on the stack + Look for #define's, check usage, create #defines if necessary + DString !! (initial dstring data in structure!) + RE's ? + NRE1 + + == running a stack test of the full test suite for a build is 1.5 hours == + == something for the evening and the night == + +Document methodology of testing stack + +Macros + TCL_NO_<feature> to deactivate/cut feature + MODULAR_TCL activates all TCL_NO_<feature> macros +------------------------------------------------------------------------ +Cut 1 + The cut currently restricts itself to the UNIX and GENERIC parts. + No changes in Win* and Mac areas. + + channel system + - no sockets TCL_NO_SOCKETS / + - no serial/tty TCL_NO_TTY / + - no pipes TCL_NO_PIPES / + - no pid command TCL_NO_PIDCMD / + - channel system provides TCL_NO_NONSTDCHAN / + only std* channels [x] + - no channel copying TCL_NO_CHANNELCOPY / + - no [read]ing TCL_NO_CHANNEL_READ / + - no [eof] [/] TCL_NO_CHANNEL_EOF / + - no channel set/get cfg TCL_NO_CHANNEL_CONFIG [+] / + - no [fblocked] TCL_NO_CHANNEL_BLOCKED [/] / + - no fileevents TCL_NO_FILEEVENTS [=] / + + filesystem + - disable filesystem TCL_NO_FILESYSTEM [%] /* + - disable load'ing TCL_NO_LOADCMD / + + master/slave interpreters + - disable slave interp TCL_NO_SLAVEINTERP /* + - disable command aliases TCL_NO_CMDALIASES /* + +[*] Access from the C level is not removed. + +[x] Implies that no .rc can be read during unix init. + Implies that no startup script can be read by tclsh. + Implies NO_SOCKETS, NO_TTY, NO_PIPES + Implies currently 'no "source" cmd' and no loading of encoding files. + In the generic case this functionality can the reimplemented by direct + OS calls without using the channel system. Makes the + implementation platform dependent. As Cisco doesn't want this functionality + we disable them without adding a new implementation. + Implies that channels cannot be moved/shared between master/slave interps. + (seek is removed under the assumption that the std* channels are not seekable) + +[/] Tcl_Eof, Tcl_InputBlocked stay because they are required by [gets]. + +[+] Tcl_SetChannelOption stays, required for initial config of std channels. + +[=] Implies no socket servers. Reason: Accept callback for socket server + is done through fev's + +[%] Ripping the filesystem intrudes heavily on the startup sequence of the + interpreter as auto_path, package paths, etc. can't be initialized anymore. + This also cuts into the initialization of encodings. + + Given that encodings will be changed later to not use UTF internally this + is no big deal. For Cisco. Others might want to have 'no fs', but UTF. + + We have to check that the startup sequence is still operational. + + Given that without a FS loading of encoding from files is + impossible the loss of initialization is again not so big a deal. + +------------------------------------------------------------------------ +------------------------------------------------------------------------ +------------------------------------------------------------------------ + +Handling of stub table when cutting features: + +1. Disable all functions for the feature, from the bottom up to + the top (script level command). This includes full disabling + of stub functions too. + + The bottom-up approach enforces link errors in the higher + levels and thus allows us to use the compiler to find all + relevant places where we have to cut. + + Cutting stub functions is essential to find everything. + +2. Go through the functions causing link errors in tclStubInit.o + == stub functions. Add variants which are empty, return errors + etc. and compile these when the feature is disabled. + + ** Changed ** + Add suppressor definitions to "tcl*.decls" and regen the code. + +------------------------------------------------------------------------ +------------------------------------------------------------------------ +------------------------------------------------------------------------ + +Future: + Implement a mechanism for 'tcl.decls' + which allows the definition of (static, loadable) sub packages. + So that the stub table is minimally initialized and + sub packages initialize their slots when loaded. + +------------------------------------------------------------------------ +------------------------------------------------------------------------ +------------------------------------------------------------------------ |