Tools Used in 6.828
If you use the MIT Athena machines that run Linux, then all the
software tools you will need for this course are located in the 6.828
locker: just type 'add 6.828' to get access to them. If
you would like to compile and run the tools on your own machine,
however, here is the information you need. Of course, we cannot
guarantee that these tools will be portable to every possible machine
you might want to run them on; they should at least compile easily on
most recent versions of Linux, however.
It should be possible to get this development environment running
under windows with the help of
Cygwin. Install cygwin, and be
sure to install the flex and bison packages
(they are under the development header).
Compiler Toolchain
Most modern Linuxes and BSDs have an ELF toolchain compatible with
the 6.828 labs. That is, the system-standard gcc,
as, ld and objdump should just work. If
your machine is in this camp, disable the i386-jos-elf- tool
prefix in your make setup by adding the following line to
conf/env.mk:
GCCPREFIX=
If you are in the minority and using something other than standard x86
linux or BSD, you will need the GNU C compiler toolchain, configured
and built as a cross-compiler for the target
'i386-jos-elf'. You can download the specific versions
we used via these links, although more recent versions of gcc and
binutils should work too:
Once you've unpacked these archives, run the following commands as root:
$ cd binutils-2.15
$ ./configure --target=i386-jos-elf
$ make
$ make install
$ cd ../gcc-3.4.1
$ ./configure --target=i386-jos-elf
$ make
$ make install
If there are errors compiling gcc when it gets to libstdc++, don't
worry about it.
Then you'll have in /usr/local/bin a bunch of binaries
with names like i386-jos-elf-gcc. It will also be
necessary to change the GNUMakefile used in the labs to use
i386-jos-elf-gcc instead of gcc. There
are instructions for how to do this inside of GNUMakefile.
Bochs Emulator
Bochs
version 2.2.6 is set up on athena for x86 machines. If you want
to use the same version on your home machine, you have two options.
- Copy the binaries from athena. Run the following commands as root:
cd /usr/local/bin
scp <username>@athena.lcs.mit.edu:/afs/athena.mit.edu/course/6/6.828/arch/linux/bin/bochs .
cd /usr/local/share
scp -r <username>@athena.lcs.mit.edu:/afs/athena.mit.edu/course/6/6.828/share/bochs bochs
- The other option is to download, compile, and install bochs from the
source archive. This is the only option if you want to run bochs under a
different OS or on a different architecture. If you download a prebuilt
version of bochs, it will not be compiled with the same options as we use for
the class. Also, the Bochs version for the class contains a bug fix to make
single-stepping work.
We've prepared an automated, self-updating script to assist you in
installing Bochs and potentially upgrading to new versions of Bochs.
As root:
# cd /some/tmp/build/dir
# wget http://pdos.lcs.mit.edu/6.828/2006/src/bochs-install.sh
# sh bochs-install.sh
If we issue future updates to our 6.828 Bochs tarball, it would only
be necessary to run:
# cd /some/tmp/build/dir
# sh bochs-install.sh
Since the script asks our server what the most current version of the
Bochs tarball is.
To do things manually,
fetch the 6.828-modified Bochs 2.2.6 source as follows:
$ wget http://pdos.lcs.mit.edu/6.828/2006/src/bochs-2.2.6-6.828r1.tar.gz
You may want to run ./configure --help and look at the
available options, particularly --prefix= which determines
where Bochs will be installed.
tar xzvf bochs-2.2.6-6.828r1.tar.gz
cd bochs-2.2.6-6.828r1
./configure --enable-disasm \
--enable-smp \
--enable-debugger \
--enable-new-pit \
--enable-all-optimizations \
--enable-4meg-pages \
--enable-global-pages \
--enable-pae \
--enable-all-optimizations \
--disable-reset-on-triple-fault \
--with-all-libs \
--with-x \
--with-x11 \
--with-nogui
make
make install
For Mac OS X Tiger:
./configure --disable-cdrom --enable-disasm \
--enable-debugger --enable-new-pit --enable-all-optimizations \
--enable-4meg-pages --enable-global-pages --enable-pae \
--enable-all-optimizations --disable-reset-on-triple-fault \
--enable-smp --with-nogui --with-x11 --with-x --with-carbon
If you wish to use a different UI than the default one, modify your
.bochsrc file accordingly. See the
bochsrc documentation. It should also be possible to just run
man bochsrc.
If you are compiling on a non-x86 platform or on windows, it may be
necessary to remove the --enable-all-optimizations flag.
If the make install step fails, it is probably possible
to install it manually by copying ./bochs to /usr/bin/bochs and
setting the environment variable BXSHARE to the path to
the bochs-2.2.6 directory.
If you want to use a different version of bochs (not recommended!),
the 6.828-specific changes are in the bx_dbg_stepN_command
function, in bx_debug/dbg_main.cc. The new function
body looks like:
void bx_dbg_stepN_command(bx_dbg_icount_t count)
{
if (count == 0) {
dbg_printf("Error: stepN: count=0\n");
return;
}
// use simulation mode while executing instructions. When the prompt
// is printed, we will return to config mode.
SIM->set_display_mode(DISP_MODE_SIM);
// single CPU
int old_guard = bx_guard.guard_for;
bx_guard.guard_for |= BX_DBG_GUARD_ICOUNT; // looking for icount
bx_guard.guard_for |= BX_DBG_GUARD_CTRL_C; // or Ctrl-C
bx_guard.guard_for &= ~BX_DBG_GUARD_IADDR_ALL;
// for now, step each CPU one instruction at a time
for (unsigned cycle=0; cycle < count; cycle++) {
for (unsigned cpu=0; cpu < BX_SMP_PROCESSORS; cpu++) {
bx_guard.icount = 1;
bx_guard.interrupt_requested = 0;
int old_mode_break = BX_CPU(cpu)->mode_break;
BX_CPU(cpu)->guard_found.guard_found = 0;
BX_CPU(cpu)->guard_found.icount = 0;
BX_CPU(cpu)->cpu_loop(1);
BX_CPU(cpu)->mode_break = old_mode_break;
}
#if BX_SUPPORT_SMP == 0
// ticks are handled inside the cpu loop
#else
BX_TICK1();
#endif
}
BX_INSTR_DEBUG_PROMPT();
bx_dbg_print_guard_results();
bx_guard.guard_for = old_guard;
}
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