[syslinux] [PATCH] git tree: libfat, chain, mtools/syslinux, menu.txt

[Michal Soltys]

On 10-08-22 14:35, Gene Cumm wrote:
>
> It writes to the disk?  That should only be done if you know things
> are bad and should probably be done by another tool (setfatgeo.c32 or
> setfatbpb.c32 might be a good tool to make), IMO.
>

Everything is controllable by the user. And by default it never writes 
anything (as well as never writes if nothing really changed).

I'll have the git branch ready to pull soon. There're few more options I 
want to add first, and I have to write doc/chain.txt (absolutely 
mandatory), to explain current options and logic. Chain is split nicely 
into 5 files (chain, partiter, utility, options, mangle).

>>  2) kernel+sector combo:
>>
>>  chain.c32 hd3 1 swap setdrv at 0x24 setgeo sethid write file=/dellbio.bin
>>  sseg=0x2000 fseg=0x70
>>
>>  This line worked fine. Note that in case when both file and sector is loaded
>>  (and the latter is mmapped), my chain.c points ds:si and ds:bp to sector
>>  instead of handover area (which is ignored in such case).
>
> Setting ds:si and ds:bp to this area: nice and convenient.
>

It's also controllable - user can set them to handover, even if sector 
would make more sense.

>>  Both options worked fine without 'swap' as well. Either way, I was greeted
>>  (on vbox vm) with dell gui (in which system test complained I wasn't dell,
>>  exit rebooted machine, memory test flashed some text quickly and didn't seem
>>  to do much).
>
> So you're trying to load at least a part of DRMK from another file
> system, if I'm interpreting things correctly?  I know that assuming
> the BPB data is set correctly for a normal FAT file system, every
> version DRMK I've tested boots perfectly from a FAT12 or FAT16 file
> system with no assistance from chain (other than what a normal MBR
> boot code will do and when I've tested this scenario; can't recall
> which ones I've tested this way).
>

I either chainloaded in typical way - read sector, adjust what needs to 
be adjusted with new options - or load dellbio.bin from syslinux 
partition (which will continues with any other partition afterwards - 
regarldes where chain.c32 is pointed to). Even if the file is being 
used, the sector can be loaded at any address / adjusted / written back 
/ etc. It's pretty flexible now.

> all I did was move the file system without correcting the BPB.  Right
> now, BOCHS is my friend for running the tests (Thank you again HPA!)
> and I'm either going to use VMware Server or BOCHS to build the disk
> images I want to test but probably BOCHS as I can play funny games on
> the geometry (tried in VMware, didn't work out).
>

Primarily I use 2 loopback-made small disk images with long partition 
chains (inc. holes) and small stub I wrote dumping interesting info 
(registers, bpb, hand areas) when it's chainloaded (from file or sector).

> After I get some more testing done to make sure my theory of loading
> DRMK and my code seem correct, I'd like to take a look at your code.
>

I should have it ready within few days at most for pulling for anyone to 
check out.