On at 2024-06-02 13:31 +0200, Bernd Böckmann via Freedos-devel wrote:
If the 10MB partition can be booted from, we have to take into account that
this is a FAT16 partition, and accordingly the FAT12/16 volume boot code is
installed. This supports both LBA and non-LBA access.
Jim, can you upload the non-working image and the working 10MB test image, so I
can have a look at the relevant data structures (MBR etc.)?
https://nextcloud.iww.rwth-aachen.de/index.php/s/BRXqZDGasw74NN9
What BIOS is this machine using?
As Jerome said, the FreeDOS installer will re-use an existing partition layout.
So what you can try (not 100% sure you already did that): start with an empty
1.9G image and install FreeDOS onto it via QEMU. The installer will create and
format a partition. Then, try to boot it with your 386.
Thinking of this LBA, non-LBA thing we might investigate if it is possible to
merge the LBA and non-LBA FAT32 VBR code into one. But that is for another
topic. We also might replace the loaders with some other one. If I remember
correctly ECMs lDOS loaders have the capability...
As we say, speak the devil's name and here she is!
I prepared an overview of the lDOS FAT32 + FSIBOOT4 loaders on my blog:
https://pushbx.org/ecm/dokuwiki/blog/pushbx/2024/0602_barely_any_work_in_the_may_june_week#ldos_fat32_boot_sector_loader_for_freedos
Comments and additional questions are welcome both in this thread or in
the comment thread of the blog.
Not listed in the article is the lDOS boot.asm (FAT12/FAT16) loader.
This one also supports the _COMPAT_FREEDOS set but it requires disabling
some of the loader's features to make the relocation code fit in the
allowed space. That is why I mention in the article that none of the
loader's features need to be disabled to use _COMPAT_FREEDOS for my
boot32.asm as a consequence of the two-stage approach.
As usual, my code is FLOSS and in the case of lDOS boot + instsect +
lmacros it builds with only NASM (a recent-ish version of the assembler
may be required).
Regards,
ecm
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