* The boot loader does now set up an IDT that allows it to catch processor
exceptions (page faults and the like). The handler dumps possibly interesting
information (registers, a (numerical) stack trace) to the serial output, and,
if possible, also to the screen. That should help debugging boot loader
crashes.
* For the IDT the boot loader sets up for the kernel the descriptors are set up
the same way, so until the kernel initializes the IDT itself (arch_init()) the
facility is still in place and can thus catch very early kernel boot crashes.
Unfortunately the on-screen output doesn't seem to work anymore at that point,
so the output only goes to the serial port...
* ... and to the debug syslog -- dprintf() does now append it there after
debug_cleanup() has been called. Seems to work fine in qemu, but when I tested
it on real hardware the debug syslog was gone.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@42092 a95241bf-73f2-0310-859d-f6bbb57e9c96

kernel:
* The kernel syslog ring buffer is no longer emptied by the syslog sender
thread. Instead we only drop the oldest data from the buffer when we're
writing to it and there's not enough free space in it.
Advantages: We drop old data rather than the most recent data when the buffer
is full. The "syslog" KDL command has more data available now. So the odds
are that kernel syslog messages not written to disk yet are at least still
in the kernel buffer.
* Changed dprintf_no_syslog() semantics: Now it writes to the syslog, but
doesn't notify the syslog sender thread.

boot loader:
* Added the ring_buffer implementation and a dummy user_memcpy().
* bios_x86: Moved the syslog stuff from serial.{cpp,h} to debug.{cpp.h}.
* Moved the debug options from the "Select safe mode options" menu to a new
"Select debug options" menu.
* Added option "Enable debug syslog" to the new menu (ATM available on x86
only). It allocates a 1 MB in-memory buffer for the syslog for this session
in such a way that it can be accessed by the boot loader after a reset.
* Added item "Display syslog from previous session" to the new menu, doing
what its name suggests.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35816 a95241bf-73f2-0310-859d-f6bbb57e9c96

* The boot loader does now set up an IDT that allows it to catch processor
exceptions (page faults and the like). The handler dumps possibly interesting
information (registers, a (numerical) stack trace) to the serial output, and,
if possible, also to the screen. That should help debugging boot loader
crashes.
* For the IDT the boot loader sets up for the kernel the descriptors are set up
the same way, so until the kernel initializes the IDT itself (arch_init()) the
facility is still in place and can thus catch very early kernel boot crashes.
Unfortunately the on-screen output doesn't seem to work anymore at that point,
so the output only goes to the serial port...
* ... and to the debug syslog -- dprintf() does now append it there after
debug_cleanup() has been called. Seems to work fine in qemu, but when I tested
it on real hardware the debug syslog was gone.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@42092 a95241bf-73f2-0310-859d-f6bbb57e9c96

kernel:
* The kernel syslog ring buffer is no longer emptied by the syslog sender
thread. Instead we only drop the oldest data from the buffer when we're
writing to it and there's not enough free space in it.
Advantages: We drop old data rather than the most recent data when the buffer
is full. The "syslog" KDL command has more data available now. So the odds
are that kernel syslog messages not written to disk yet are at least still
in the kernel buffer.
* Changed dprintf_no_syslog() semantics: Now it writes to the syslog, but
doesn't notify the syslog sender thread.

boot loader:
* Added the ring_buffer implementation and a dummy user_memcpy().
* bios_x86: Moved the syslog stuff from serial.{cpp,h} to debug.{cpp.h}.
* Moved the debug options from the "Select safe mode options" menu to a new
"Select debug options" menu.
* Added option "Enable debug syslog" to the new menu (ATM available on x86
only). It allocates a 1 MB in-memory buffer for the syslog for this session
in such a way that it can be accessed by the boot loader after a reset.
* Added item "Display syslog from previous session" to the new menu, doing
what its name suggests.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35816 a95241bf-73f2-0310-859d-f6bbb57e9c96