98ddbffe6e
- it can disassemble object files (dis386o) and executables
(dis386a)
- only useful for as long as we still have ack
78 lines
2.9 KiB
Plaintext
78 lines
2.9 KiB
Plaintext
Dis36: a static disassembler for Minix 2.0. C W Rose, 20 Oct 97.
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SUMMARY
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This is the second release of dis386, a disassembler for Minix 2.0 At present
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it is comprised of two programs, dise which understands executable files, and
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diso which understands object files. The programs have been written using as
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much common code as possible, and in time they will be merged. Meantime, they
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are easier to debug separately.
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The two programs are both front ends for Bruce Evan's x86 disassembler. The
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disassembler can handle both 16-bit and 32-bit code, but since the programs
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use large data tables (kept in memory for speedy access) they have been tested
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only on 32-bit Minix.
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The changes between versions 1.0 and 1.1 are small, but add to the ease of
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use: addresses can now be entered in decimal or hexadecimal (leading 0x),
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and starting offset and program counter now have more intelligble values.
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OPTIONS
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Object, executable and core files have the following structures, where
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Name is the section name, and Option the option needed to display the section.
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Object file Executable file Core file
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Name Option Name Option Name Option
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Header } h Header h Memory map m
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Section headers } Process table p
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Sections - Sections - Sections -
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text t text t text t
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rom m
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data d data d data d
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bss - stack k
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Relocation structures r
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Symbol table s Symbol table s
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Symbol names n
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Other options are:
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-A str set executable file name
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-C str set core file name
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-O str set object file name
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-a display all sections
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-b dump in straight binary
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-f # set the first address to be displayed
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-l # set the last address to be displayed
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-x # set debugging level
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Not all these options are functional at present; in particular, the file type
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override of -A/C/O isn't implemented (since the programs are single-purpose).
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The default option is -h. The default input file is a.out for dise, and test.o
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for diso. Otherwise, input is taken from the first file option on the command
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line. Output is always written to standard output, and error messages to
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standard error.
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BUGS AND FEATURES
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The programs search the data area for possible local symbols; generally, these
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are the start of strings. At the moment this search is limited, and accepts
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even single printing characters as strings; it should probably accept only
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runs of three or more characters.
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There is no search for local text symbols, as opposed to data symbols; this
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would need two full passes over the text with the disassembler, and doesn't
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seem worthwhile. Once the data symbols are out of the way, the disassembled
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text is fairly easy to read.
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The programs do a fair amount of error checking to ensure that they are
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using eg. addresses that are within scope, but if they do fail they tend
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to abandon the task completely and bale out with a (supposedly informative)
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error message.
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There are many apparent dead-ends in the code, left as hooks for later
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additions.
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/* eof */
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