Can't get a rom image below 512k?

Andrew Kohlsmith akohlsmith-linuxbios at
Thu Nov 14 00:09:01 CET 2002

> It will work.  I don't think your kernel is flakey. If anything, I think
> the problem is elsewhere.  And I think the fault is in the simulator,
> but I can't get the Bochs team to agree one way, or the other, with my
> suggestions regarding this project. Yes, please do.

Oops...  It doesn't commit suicide when at 0x04000; it is doing more 
unpacking.  I am now tracing it printing "LinuxBIOS", trying to see where it 
*does* jump off in to never-never land, eventually tripping bochs out by 
going over my memory size.

Yes, I figured out why it was giving me that error -- just after returning 
from the PCI mapping (it prints the string "PCI: pci_scan_bus for bus %d" (I 
guess I'm in a printf()), it tries jumping to a far pointer but fails.  (the 
pointer points to 0x0000, which (I think) is the GDT, followed by a whole lot 
of nuthin'.  :-)  I've included a bit of the trace at the end of this email.

The crash always occured at the 16M mark, where is what I have my RAM size set 
to.  I guess there was enough random data in RAM that got it to jump over the 
RAM image and continue on to the end of RAM.


(0).[545025] 0010:00007246 (unknown context): 55: push EBP
(0).[545026] 0010:00007247 (unknown context): 89e5: mov EBP, ESP
(0).[545027] 0010:00007249 (unknown context): ff7514: push SS:[EBP + 14]
(0).[545028] 0010:0000724c (unknown context): 0fb64510: movzx EAX, SS:[EBP + 
(0).[545029] 0010:00007250 (unknown context): 50: push EAX
(0).[545030] 0010:00007251 (unknown context): 0fb6450c: movzx EAX, SS:[EBP + 
(0).[545031] 0010:00007255 (unknown context): 50: push EAX
(0).[545032] 0010:00007256 (unknown context): 0fb64508: movzx EAX, SS:[EBP + 
(0).[545033] 0010:0000725a (unknown context): 50: push EAX
(0).[545034] 0010:0000725b (unknown context): a140b50000: mov EAX, 
(0).[545035] 0010:00007260 (unknown context): ff5008: call DS:[EAX + 08]
(0).[545036] 0010:00000000 (unknown context): 0201: add AL, DS:[ECX]
(0).[545037] 0010:00000002 (unknown context): 0000: add DS:[EAX], AL

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