the kernel. They are not used atm, but having them in trunk allows them
to be easily used when needed. To set a breakpoint that triggers when
the variable foo is written to (the most common use case), one calls:
breakpoint_set(vir2phys((vir_bytes) &foo), 0,
BREAKPOINT_FLAG_MODE_GLOBAL |
BREAKPOINT_FLAG_RW_WRITE |
BREAKPOINT_FLAG_LEN_4);
It can later be disabled using:
breakpoint_set(vir2phys((vir_bytes) &foo), 0,
BREAKPOINT_FLAG_MODE_OFF);
There are some limitations:
- There are at most four breakpoints (hardware limit); the index of the
breakpoint (0-3) is specified as the second parameter of
breakpoint_set.
- The breakpoint exception in the kernel is not handled and causes a
panic; it would be reasonably easy to change this by inspecing DR6,
printing a message, disabling the breakpoint and continuing. However,
in my experience even just a panic can be very useful.
- Breakpoints can be set only in the part of the address space that is
in every page table. It is useful for the kernel, but to use this for
user processes would require saving and restoring the debug registers
as part of the context switch. Although the CPU provides support for
local breakpoints (I implemened this as BREAKPOINT_FLAG_LOCAL) they
only work if task switching is used.
UPDATING INFO:
20100317:
/usr/src/etc/system.conf updated to ignore default kernel calls: copy
it (or merge it) to /etc/system.conf.
The hello driver (/dev/hello) added to the distribution:
# cd /usr/src/commands/scripts && make clean install
# cd /dev && MAKEDEV hello
KERNEL CHANGES:
- Generic signal handling support. The kernel no longer assumes PM as a signal
manager for every process. The signal manager of a given process can now be
specified in its privilege slot. When a signal has to be delivered, the kernel
performs the lookup and forwards the signal to the appropriate signal manager.
PM is the default signal manager for user processes, RS is the default signal
manager for system processes. To enable ptrace()ing for system processes, it
is sufficient to change the default signal manager to PM. This will temporarily
disable crash recovery, though.
- sys_exit() is now split into sys_exit() (i.e. exit() for system processes,
which generates a self-termination signal), and sys_clear() (i.e. used by PM
to ask the kernel to clear a process slot when a process exits).
- Added a new kernel call (i.e. sys_update()) to swap two process slots and
implement live update.
PM CHANGES:
- Posix signal handling is no longer allowed for system processes. System
signals are split into two fixed categories: termination and non-termination
signals. When a non-termination signaled is processed, PM transforms the signal
into an IPC message and delivers the message to the system process. When a
termination signal is processed, PM terminates the process.
- PM no longer assumes itself as the signal manager for system processes. It now
makes sure that every system signal goes through the kernel before being
actually processes. The kernel will then dispatch the signal to the appropriate
signal manager which may or may not be PM.
SYSLIB CHANGES:
- Simplified SEF init and LU callbacks.
- Added additional predefined SEF callbacks to debug crash recovery and
live update.
- Fixed a temporary ack in the SEF init protocol. SEF init reply is now
completely synchronous.
- Added SEF signal event type to provide a uniform interface for system
processes to deal with signals. A sef_cb_signal_handler() callback is
available for system processes to handle every received signal. A
sef_cb_signal_manager() callback is used by signal managers to process
system signals on behalf of the kernel.
- Fixed a few bugs with memory mapping and DS.
VM CHANGES:
- Page faults and memory requests coming from the kernel are now implemented
using signals.
- Added a new VM call to swap two process slots and implement live update.
- The call is used by RS at update time and in turn invokes the kernel call
sys_update().
RS CHANGES:
- RS has been reworked with a better functional decomposition.
- Better kernel call masks. com.h now defines the set of very basic kernel calls
every system service is allowed to use. This makes system.conf simpler and
easier to maintain. In addition, this guarantees a higher level of isolation
for system libraries that use one or more kernel calls internally (e.g. printf).
- RS is the default signal manager for system processes. By default, RS
intercepts every signal delivered to every system process. This makes crash
recovery possible before bringing PM and friends in the loop.
- RS now supports fast rollback when something goes wrong while initializing
the new version during a live update.
- Live update is now implemented by keeping the two versions side-by-side and
swapping the process slots when the old version is ready to update.
- Crash recovery is now implemented by keeping the two versions side-by-side
and cleaning up the old version only when the recovery process is complete.
DS CHANGES:
- Fixed a bug when the process doing ds_publish() or ds_delete() is not known
by DS.
- Fixed the completely broken support for strings. String publishing is now
implemented in the system library and simply wraps publishing of memory ranges.
Ideally, we should adopt a similar approach for other data types as well.
- Test suite fixed.
DRIVER CHANGES:
- The hello driver has been added to the Minix distribution to demonstrate basic
live update and crash recovery functionalities.
- Other drivers have been adapted to conform the new SEF interface.
Move archtypes.h to include/ dir, since several servers require it. Move
fpu.h and stackframe.h to arch-specific header directory. Make source
files and makefiles aware of the new header locations.
-Convert the include directory over to using bsdmake
syntax
-Update/add mkfiles
-Modify install(1) so that it can create symlinks
-Update makefiles to use new install(1) options
-Rename /usr/include/ibm to /usr/include/i386
-Create /usr/include/machine symlink to arch header files
-Move vm_i386.h to its new home in the /usr/include/i386
-Update source files to #include the header files at their
new homes.
-Add new gnu-includes target for building GCC headers
- put asmconv in /usr/bin so it can be invoked without absolute path
- make it ignore .end in gnu output mode so that it can be invoked
without '|| true' in the gnu lib makefiles and it doesn't produce the
messy error message
- PM: get rid of umap warning
- sprofalyze.pl: update with recently added servers and drivers
- sprofalyze.pl: properly truncate process names for sample matching
ow that the image has grown beyond the 1.44M that fits on a floppy.
(previously, the floppy emulation mode was used for cd's.)
the boot cd now uses 'no emulation mode,' where an image is provided on
the cd that is loaded and executed directly. this is the boot monitor.
in order to make this work (the entry point is the same as where the
image is loaded, and the boot monitor needs its a.out header too) and
keep compatability with the same code being used for regular booting, i
prepended 16 bytes that jumps over its header so execution can start
there.
to be able to read the CD (mostly in order to read the boot image),
boot has to use the already present 'extended read' call, but address
the CD using 2k sectors.
- allow mounting with "none" block device
- allow unmounting by mountpoint
- make VFS aware of file system process labels
- allow m3_ca1 to use the full available message size
- use *printf in u/mount(1), as mount(2) uses it already
- fix reference leaks for some mount error cases in VFS
