[syslinux] Embedding com32 modules and ldlinux.sys into one file

[Celelibi]

2016-01-12 22:21 UTC+01:00, Tal Lubko via Syslinux <syslinux at zytor.com>:
> On Mon, Jan 11, 2016 at 07:20:20PM -0500, Shao Miller via Syslinux wrote:
>> Good day, Tal.
>>
>> Perhaps if you describe a little bit more about the rationale behind
>> this single-file requirement, someone might be able to make an
>> alternative suggestion that you haven't thought of.
>>
>> The BIOS- and disk-based Syslinux bootstrapping actually often has a
>> filesystem-specific piece of code that lives in the filesystem's
>> meta-data, as well as the primary file and COMBOOT32 modules that
>> you are thinking of.  Because of that first piece, it's not really
>> possible to have this kind of Syslinux as a single file.
>>
>> But if you were to share a few more details, perhaps you're thinking
>> of a PXE environment or a CD environment or a new filesystem or...?
>> Are you able to describe the sequence of boot-up events that occur
>> before the point you are thinking of?
>>
>> Yes, you can print debug-output from custom builds.
>>
>
> Hi Shao
>
> The requirement is for the bootloader to be stored on the BIOS flash chip
> which will be read only.
> The BIOS will be modified to load bootloader from this chip.
> To simplify things and to avoid the need for a file system, I thought to
> store the bootloader as a single file.
> I don't reject the idea of using a very simple file-system to store the
> different bootloader files and loading it into RAM.
>
> Diving in I understand there are probably more difficulties I'll have to
> face.
> I'll be glad to get experts opinions and ideas about the difficulties I'll
> have to face and how to face it.
>
> Regarding my other question (debugging). I know it is possible to use
> prints
> for debugging.
> I wonder if there is another way.

In qemu it is possible to have source-level debugging, all you need to
know is the address at which the code is loaded to tell gdb where to
relocate the debugging symbols.

On real hardware, I think there's a support for serial port, but I've
never used it.