RE: LinuxBIOS debugging with an emulator

> On Tue, 26 Oct 2004 [e-mail] wrote:
> > Can someone tell me what the starting sequence is with LinuxBIOS?
> >
> > Reset jumps to crt0.s.  crt0.s calls auto.E.  auto.E is built using
> > romcc, so source-level debugging is not possible.
>
> ah well :-)
> > The statement
> > locations can be found using the Lxxxx labels in linuxbios.map.

Then
> > hardwaremain is called. Hardwaremain is the first C function called.
>
> yep.
> > Crt0 and auto run out of FLASH.  Hardwaremain is the first function
> > called after LinuxBIOS is copied to RAM.
>
> sounds good so far.
>
> ron

It seems that LinuxBIOS copies itself to _RAMBASE, which is 0x4000.
Then it branches to 0x4000 into _start, which sets up the stack and
calls hardwaremain.  The address of hardwaremain from linuxbios_c.o is
wrong.  The address is not the Flash address and it's not the RAM
address.  Can someone explain how linuxbios_c.o is linked with RAM
addresses?

Steve

LinuxBIOS debugging with an emulator

[Li-Ta Lo]

On Thu, 2004-10-28 at 16:03, [e-mail] wrote:
> It seems that LinuxBIOS copies itself to _RAMBASE, which is 0x4000.
> Then it branches to 0x4000 into _start, which sets up the stack and
> calls hardwaremain.  The address of hardwaremain from linuxbios_c.o is
> wrong.  The address is not the Flash address and it's not the RAM
> address.  Can someone explain how linuxbios_c.o is linked with RAM
> addresses?

What do you mean ? In the S2885 I built, the _RAMBASE is 0x4000 and 
hardwaremain is 0x5fe0 as you can get from the linuxbios_c.map. They
are both in RAM. If you use "objdump -drS linuxbios_c.o" you will
find the hardwaremain is at offset 0x1fe0 from the _RAMBASSE.

BTW, if you specify the -g option for gcc, you can use the -S option
in objdump to see the source code with the disassebmly (-d).

Ollie
> Steve 
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LinuxBIOS debugging with an emulator

[Adam Sulmicki]

On Thu, 28 Oct 2004, Li-Ta Lo wrote:
> BTW, if you specify the -g option for gcc, you can use the -S option
> in objdump to see the source code with the disassebmly (-d).

BTW, this is a very usefull tip. I had been using it lately all the time
to trace ooops in kernel.

objdump -S -C ./vmadump.ko  |less