freeldr as PE file

[Timo Kreuzer]

Hi

I'd like to propose a small change: converting freeldr into a PE file.

The current freeldr / setupldr are raw binaries, which makes them easy
to handle for the bootsector but it disqualifies them from proper
debugging with gdb. A solution is to convert them into PE format. As
there is no space to implement a real PE loader in the bootsector, the
image must not use a .bss section, this can easily be done with a linker
script.
I have this working in my WC.
With the result we can use gdb for debugging freeldr including symbols.
The only thing still to solve is how to remove rsym data from the files,
without stripping all symbols. Rsym data makes the file twice as big,
too big to be loaded in to real mode memory.

Any objections / suggestions?

Regards,
Timo

[Brian Palmer]

IIRC, there is currently some extra boot code prepended to the beginning of
the FreeLoader binary to assist the bootsector on certain file systems. Does
converting to PE format cause any problems for this?

-----Original Message-----
From: ros-dev-bounces(a)reactos.org [mailto:[e-mail]] On
Behalf Of Timo Kreuzer
Sent: Saturday, July 17, 2010 8:52 PM
To: ReactOS Development List
Subject: [ros-dev] freeldr as PE file

Hi

I'd like to propose a small change: converting freeldr into a PE file.

The current freeldr / setupldr are raw binaries, which makes them easy
to handle for the bootsector but it disqualifies them from proper
debugging with gdb. A solution is to convert them into PE format. As
there is no space to implement a real PE loader in the bootsector, the
image must not use a .bss section, this can easily be done with a linker
script.
I have this working in my WC.
With the result we can use gdb for debugging freeldr including symbols.
The only thing still to solve is how to remove rsym data from the files,
without stripping all symbols. Rsym data makes the file twice as big,
too big to be loaded in to real mode memory.

Any objections / suggestions?

Regards,
Timo


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[Timo Kreuzer]

Brian Palmer schrieb:
>   IIRC, there is currently some extra boot code
> prepended to the beginning of
>  the FreeLoader binary to assist the bootsector on certain file systems. Does
>  converting to PE format cause any problems for this?
>     
Yes, you are right, this might cause problems. I'll look into it. We
probably need to replace the fathelper code at the beginning with an
additional binary file.

[Brian Palmer]

IMO, it would be preferable not to have two separate filesystem files
required for the bootsector to load in and boot with. My vote would be for
the fat helper code to stay where it is, even at the expense of easier GDB
debugging. Although, I was always content with the serial port output to
debug FreeLoader. Of course, if GDB support could be enabled without making
the boot code harder to manage, that would be great also.

-----Original Message-----
From: ros-dev-bounces(a)reactos.org [mailto:[e-mail]] On
Behalf Of Timo Kreuzer
Sent: Tuesday, July 20, 2010 1:30 PM
To: ReactOS Development List
Subject: Re: [ros-dev] freeldr as PE file

Brian Palmer schrieb:
>   IIRC, there is currently some extra boot code
> prepended to the beginning 
of
>   the FreeLoader binary to assist the bootsector on
> certain file systems. 
Does
>   converting to PE format cause any problems for this?
>     
Yes, you are right, this might cause problems. I'll look into it. We
probably need to replace the fathelper code at the beginning with an
additional binary file.


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