Cliff added to bios_printf the ability to print onto the console. Bryce made
some further changes. Now when a panic occurs, the message is reported both
to the Bochs log file and to the screen, and then it goes into an infinite
busy loop. Why an inf loop? If I do a HLT in BIOS code, current bochs
versions will panic immediately and the user will never see the real panic
message. I have mostly tested the new panic behavior by booting nonbootable
and nonreadable disks.
are released, I will remove VGABIOS-cbothamy-0.2a and add a file with
the other version number. I decided not to use the "-latest" naming
scheme because there is no synchronization between bochs releases and
LGPL VGA BIOS releases. Anything that's called "latest" is bound to
go obsolete eventually.
a read-only disk image. For systems such as DOS that actually use the
BIOS services, it was also necessary to add code in int13_diskette_function
to recognize a write-protected error and return the correct error
status code (AH=3, Carry Set).
[ #430472 ] DOS HIMEM "A20 line" error
All I've done is moved the call to print_bios_banner later in the
boot process, and the A20 problem goes away. I wanted it early so
that it would get printed before any panic or halt could happen.
Oh well.
by BCC generated data. This was pointed out by Tom Lindström
<tom@debet.shh.fi>, and I took his suggestion of moving the MP structures
to the end of the file.
- now the HALT macro in rombios.c writes to panic port but does not actually
execute a "hlt" instruction. This allows the .bochsrc to control
whether the BIOS panic is fatal or not.
His change log says:
- Makefile simplified - no longer uses tools86, dataseghack or ld86.
Also enables warnings (-w-) and checks for undefined labels (-u-).
- Macros used in place of multi-line #defines (so !!! conversion by
tools86 not needed).
- HALT() fixed [previously used ';' instead of '!!!']. Needs port 400 to
be added to iodev to be useful?
- isru removed - doesn't seem to be needed now.
- added UDIV16 (for use by bios_printf).
- bios_printf %d implemented.
- set_enable_a20 changed to use PS2 method, since bochs emulates this.
- Keyboard intercept (int 15h/42h) fixed - should set CF, not assume that
caller already has. [The DOS keyb driver for example doesn't!]
- Memory is scanned from C000 to F4000 for extension ROMs - this
picks up VGA BIOS as before, and allows others to be included.
- Comments improved for bios config table, and bit indicating RTC
present is now set.
- Int 9 (keyboard) now calls Int 15h/42h for key releases too.
[Again, this is what the DOS keyb driver does.]
in BRANCH-smp-bochs revisions.
- The general task was to make multiple CPU's which communicate
through their APICs. So instead of BX_CPU and BX_MEM, we now have
BX_CPU(x) and BX_MEM(y). For an SMP simulation you have several
processors in a shared memory space, so there might be processors
BX_CPU(0..3) but only one memory space BX_MEM(0). For cosimulation,
you could have BX_CPU(0) with BX_MEM(0), then BX_CPU(1) with
BX_MEM(1). WARNING: Cosimulation is almost certainly broken by the
SMP changes.
- to simulate multiple CPUs, you have to give each CPU time to execute
in turn. This is currently implemented using debugger guards. The
cpu loop steps one CPU for a few instructions, then steps the
next CPU for a few instructions, etc.
- there is some limited support in the debugger for two CPUs, for
example printing information from each CPU when single stepping.
Christophe Bothamy