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

[Tal Lubko]

> -----Original Message-----
> From: Sergii Kolisnyk [mailto:kolkmail at gmail.com]
> Sent: Tuesday, January 19, 2016 2:35 PM
> To: Syslinux
> Cc: Tal Lubko
> Subject: Re: [syslinux] Embedding com32 modules and ldlinux.sys into
> one file
> 
> Hi, Tal,
> 
> could you answer to 2 questions:
> - what is amount of ROM you're intending to use?
> (actually 8 MB SPI or parallel NOR flash chip can contain some
> minimalist Linux distribution)

The size of the ROM chip I'm going to use will be at least 16 MB.
I'm not sure how big the BIOS image is but probably I'll have enough room for Linux image there as well.
I want to avoid it because:
- It will be harder to upgrade Linux image located on ROM
- It will be probably much slower to load Linux image located on ROM

> - which chip do you plan to flash to, motherboard BIOS or option ROM?

If I understand you correctly, I'm going to flash the motherboard BIOS.

> Also, ROMOS comes without a license, so you'll have to contact the
> author for commercial usage.
> On other hand, ROMDSK is GPLed, and you can just comply. I would
> suggest to actually try both.

OK

> For ROM disk sizes greater than 62kB, which can't fit into a window in
> low memory, you will need to use some other memdisk code, utilizing
> either protected mode or flash controller in IO mode.

I don't understand completely what you wrote and probably lack some knowledge about protected mode, IO mode etc.
Why does ROM disk should fit low memory?

> You are welcome,
> Sergii
> 
> On 19/01/2016, Tal Lubko via Syslinux <syslinux at zytor.com> wrote:
> >
> >
> >> -----Original Message-----
> >> From: H. Peter Anvin [mailto:hpa at zytor.com]
> >> Sent: Friday, January 15, 2016 8:41 PM
> >> To: Tal Lubko; 'Celelibi'
> >> Cc: 'For discussion of Syslinux and tftp-hpa'
> >> Subject: Re: [syslinux] Embedding com32 modules and ldlinux.sys into
> >> one file
> >>
> >> On 01/14/2016 02:50 PM, H. Peter Anvin via Syslinux wrote:
> >> > On 01/13/16 00:13, Tal Lubko via Syslinux wrote:
> >> >>
> >> >> OK. I'll try that.
> >> >> Any thoughts regarding the requirement to store the bootloader
> >> inside the BIOS chip?
> >> >>
> >> >
> >> > That is fundamentally up to your BIOS.  The best is to expose the
> >> > bootloader in the BIOS as a (readonly) disk drive using standard
> >> > BIOS or EFI interfaces.
> >> >
> >>
> >> Now, if you are using EFI, you might just want to consider just
> >> running the kernel itself as an EFI executable.
> >>
> >> If with "bootloader in memory" you mean the whole firmware package,
> >> look at EDK2, Coreboot, or uboot.
> >>
> >> 	-hpa
> >>
> >
> > Hi
> >
> > Thanks a lot for the answers given.
> > I think I should change this conversion topic to "storing the
> > bootloader inside the BIOS chip" or something similar.
> > I now understand a little bit more about the boot process and see
> that
> > it is more complicated than just Embedding the com32 module into
> ldlinux.sys.
> >
> > To summarize the answers, the option I see now are:
> >
> > 1) Exposing the bootloader in the BIOS as a (readonly) disk drive
> > using standard BIOS or EFI interfaces (hpa suggestion).
> > This suggestion looks very promising. It probably requires some
> > changes in the BIOS. I'm not sure if it requires changes in the
> bootloader.
> > There is one potential problem I see: the bootloader is stored on
> some
> > flashrom chip and the Linux image is stored on a different storage
> device.
> > I think that right now the bootloader assumes they are stored on the
> > same storage device. Am I wrong?
> > If I'm wrong, how do I tell the bootloader to load the Linux image
> > from a different storage device?
> >
> > 2) The ROMOS project (Sergii suggestion).
> > As far as I understand, basically this project creates virtual ROM
> > disk image that can be used for the boot sequence. So this is somehow
> > similar to hpa suggestion.
> > I'll try to play with it a little bit.
> >
> > 3) EDK2, Coreboot, or uboot.
> > I can say nothing about it right now.
> >
> > Thanks again for your help,
> > Tal
> >
> >
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