[SeaBIOS] SeaBIOS not fully working when compiled on FreeBSD

Kevin O'Connor kevin at koconnor.net
Thu Apr 16 03:43:19 CEST 2015


On Wed, Apr 15, 2015 at 07:31:21PM +0200, Roger Pau Monné wrote:
> Hello,
> 
> I've compiled SeaBIOS on FreeBSD with gcc48, and although the build 
> process succeeds, the resulting binary doesn't fully work. Most 
> functions seem to work fine but there are some int15h functions that 
> don't work properly (ie: they return invalid values).
> 
> I've compiled SeaBIOS with CONFIG_DEBUG_LEVEL=10 and got the following 
> output (this is from the Xen console):

I'd be careful with debug level 10 - I've seen the high debugging
cause issues.  I usually don't go above 8.  Alternatively, you can
decrease the individual debug levels in src/config.h .

> [...]
> (d4) enter handle_1a:
> (d4)    a=00000200  b=00000000  c=00001725  d=00003400 ds=4cf0 es=9eb8 ss=dd00
> (d4)   si=00000004 di=00000000 bp=00000000 sp=0000fe66 cs=0000 ip=9336  f=0242
> (d4) enter handle_1a:
> (d4)    a=00000200  b=00000000  c=00001725  d=00003400 ds=4cf0 es=9eb8 ss=dd00
> (d4)   si=00000004 di=00000000 bp=00000000 sp=0000fe66 cs=0000 ip=9336  f=0242
> (d4) enter handle_1a:
> (d4)    a=00000200  b=00000000  c=00001725  d=00003400 ds=4cf0 es=9eb8 (XEN) irq.c:386: Dom4 callback via changed to Direct Vector 0x93
> (XEN) irq.c:276: Dom4 PCI link 0 changed 5 -> 0
> (XEN) irq.c:276: Dom4 PCI link 1 changed 10 -> 0
> (XEN) irq.c:276: Dom4 PCI link 2 changed 11 -> 0
> (XEN) irq.c:276: Dom4 PCI link 3 changed 5 -> 0
> (d4) enter handle_15:
> 
> And that's all, there's no line containing the register values. I'm 
> quite lost at figuring what's going on, so any help about how to 
> proceed in order to debug this is highly appreciated.

In situations like the above, I run qemu with "-d in_asm,int,exec,cpu"
and redirect the output to some log file.  I then look through the log
to see where things went wrong.

If you know which "int 15h" is returning bogus values, you can also
use gdb with qemu and set a break point.  See
http://seabios.org/Debugging .

Let me know what you find or if you need help.
-Kevin



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