From 397b86b79ae86c92946ed22a11854bc404a2285f Mon Sep 17 00:00:00 2001 From: mainzelm Date: Tue, 26 Nov 2002 12:09:44 +0000 Subject: [PATCH] Removed documentation for the static linker: it never worked for 0.6 anyway. --- doc/scsh-manual/running.tex | 125 ------------------------------------ 1 file changed, 125 deletions(-) diff --git a/doc/scsh-manual/running.tex b/doc/scsh-manual/running.tex index a2dad7f..b89d7d2 100644 --- a/doc/scsh-manual/running.tex +++ b/doc/scsh-manual/running.tex @@ -785,131 +785,6 @@ heap image. One occasionally hears rumours that this is being addressed by the {\scm} development team. -\section{Statically linking heap images} -The static heap linker converts a {\scm} bytecode image contained -in a .image file to a C representation. This C code is then compiled and -linked in with a virtual machine, producing a single executable. -Some of the benefits are: -\begin{itemize} - \item Instantaneous start-up time. - \item Improved paging; scsh images can be shared between different - processes. - \item Vastly reduced GC copying---the whole initial image - is moved out of the heap, and neither traced nor copied. - \item Result program no longer depends on the filesystem for its - initial image. -\end{itemize} - -The static heap linker takes arguments in the following form: -\codex{scsh-hlink \var{image} \var{executable} [\var{option} \ldots]} -It reads in the heap image \var{image}, translates it into C code, -compiles the C code, and links it against the scsh vm, producing the -standalone binary file \var{executable}. - -Each C file represents part of the heap image as a constant C \ex{long} vector -that looks something like this: -{\small\begin{verbatim} -const long p116[]={0x882,0x24,0x19, - 0x882,(long)(&p19[785])+7,(long)(&p119[125])+7, - 0x882,(long)(&p119[128])+7,(long)(&p119[131])+7, - 0x882,(long)(&p102[348])+7,(long)(&p3[114])+7, - 0xfc2,0x2030200,0x7100209,0x1091002,0x1c075a, - 0x882,(long)(&p29[1562])+7,(long)(&p119[137])+7, - 0x882,(long)(&p78[692])+7,(long)(&p119[140])+7, - . - . - . - }; -\end{verbatim}}% -% -Translating to a C declaration gives us freedom from the various -object-file formats.\footnote{This idea is due to Jonathan Rees.} -Note that the const declaration allows the compiler to put this array in the -text pages of the executable. -The heap is split into parts because many C compilers cannot handle -multi-megabyte initialised vector declarations. - -The allowed options to the heap linker are: -\begin{itemize} -\def\Item#1{\item{\ex{#1}}\\} - -\Item{--temp \var{dir}} The temporary directory to hold .c and .o files. - The default is typically configured to be - \ex{/usr/tmp}, and can be overridden by the - environment variable \ex{TMPDIR}. - Example: - \codex{--temp /tmp} - -\Item{--cc \var{command}} The command to run the C compiler. - The default can be overridden by the environment - variable \ex{CC}. - Example: - \codex{--cc "gcc -g -O"} - -\Item{--ld \var{command}} The arguments to run the C compiler as a linker. - The default can be overridden by the - environment variable \ex{LDFLAGS}. - Example: - \codex{--ld "-Wl,-E"} - -\Item{--libs \var{libs}} The libraries needed to link the VM and heap. - The default can be overridden by the - environment variable \ex{LIBS}. - Example: - \codex{--libs "-ldld -lld -lm"} -\end{itemize} - -Be warned that the current heap linker has many shortcomings. -\begin{itemize} -\item It is extremely slow. Really, really slow. Translating the standard - scsh heap image into a standalone binary takes well over an hour on a - 40Mb/133Mhz Pentium system. - A memory-starved 486 could take all night. - -\item It cannot be applied to itself. The current implementation - works by replacing some of the heap-dumping code. This means - you cannot load the heap-linker code into a scsh system and - subsequently use \ex{dump-scsh-program} to create a heap-linker - heap image. - -\item The interface leaves a lot to be desired. - \begin{itemize} - \item It requires the heap image to be referenced by a file-name; - the linker will not allow you to feed it the input heap image - on a port. - \item The heap-image is linked against the vm contained in -\begin{tightcode} -/usr/local/lib/scsh/libscshvm.a\end{tightcode} - This is wired in at the time scsh is installed on your system. - \item There is no Scheme procedural interface. - \end{itemize} - -\item The program produced uses the default VM argv parser \verb|process_args| - from the scsh source file \ex{main.c} to process the command line - before handing it off to the heap image's top-level procedure. - This is not what you want for many programs. - - The system needs to be changed to allow users to override this default - with their own VM argument parsers. - -\item A possible problem is the Unix limits on the number of command - line arguments. The heap-linker calls the C linker with a large number of - object files. Its conceivable that on some Unix systems this could fail - now or if scsh grows in the future. The solution could be to create - library archives of a few dozen files and then link the result few dozen - library archives to make the executable. -\end{itemize} - -In spite of these many shortcomings, we are providing the static linker -as it stands in this release so that people may get some experience with -it. - -Here is an example of how one might use the heap linker: -\begin{code} - scsh-hlink scsh.image fastscsh\end{code} - -We'd love it if someone would dive into the source and improve it. - %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Standard file locations} Because the scshvm binary is intended to be used for writing shell