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

Tal Lubko tallubko at yahoo.com
Wed Jan 13 00:13:44 PST 2016



> -----Original Message-----
> From: Celelibi [mailto:celelibi at gmail.com]
> Sent: Wednesday, January 13, 2016 2:22 AM
> To: Tal Lubko
> Cc: Shao Miller; For discussion of Syslinux and tftp-hpa
> Subject: Re: [syslinux] Embedding com32 modules and ldlinux.sys into
> one file
> 
> 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.

OK. I'll try that.
Any thoughts regarding the requirement to store the bootloader inside the BIOS chip?




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