--- Giacomo Catenazzi <cate@math.ethz.ch> a écrit :
> Etienne Lorrain wrote:
> > These two files in memory have also to be at fixed linear
> > addresses in real mode - and if you have a memory manager
> > (himem.sys) loaded, these address may not be free. Usually
> > you will find at the bottom of the himem memory the smartdrv
> > (disk cache) data. It is then impossible to load a file at a random
> > memory address and stay in real mode to do futher processing.
> > In this case, Gujin is just malloc'ing the memory (using himem.sys),
> > loading and decompressing this file (checking its CRC32), and
> > only then disable interrupts, switch to protected mode, copy
> > the file at its intended linear address and jump to the kernel
> > code.
> >
>
> hmm.
>
> You say: BIOS/hardware can be broken, let use DOS do load Linux!
There are ISA/PCI cards which are initialised before the first sector
of the HD/FD is loaded (SCSI, network boot ROM or special devices), but
it is true that they are not usually using memory at 0x100000.
I have just done this relocation thinking that it may be nice to be
able to load a kernel over the 16 Mbytes limit - to free a maximum
of space to the 16 Mb DMA-able area (if DMA is 16 Mb only) - but that
is stuff for the future because the kernel would be linked at another
address. I applied this late-relocation in case of himem.
> IMHO using DOS (himem.sys and letting DOS to setting our
> hardware in ibmbio.com and ibmdos.com) give us more problem
> that solution!
I am not able to open the A20 gate in all the ways himem.sys can,
objdump will be your friend here. Note that Linux has never booted
on such a special machine - using I/O ports 0x329 or 0x320 to open A20 -
I just leave the door open to run from DOS/win, even for beginner
who do not know what is himem/emm386 - or people wanting to remote
boot Linux from a DOS/win machine getting vmlinuz from the network.
> We should have complete control to hardware, not letting DOS
> to hide/modify the BIOS segment 0040:0000 and some other
> hardware setting.
So Gujin will boot from an IDE HD not supported by the BIOS,
on a VGA card without BIOS (or nearly: see VGA_MEMORY compile switch).
It can also do what loadlin does - I do not want to maintain two
identical software.
> Thus we should (if possible) use only BIOS call (or directly hardware),
> but forget DOS. (BTW you know what DOS makes before himem.sys ?
> Do we have the sources?)
Forget DOS/Win - what a dream... Can I join your dream?
Etienne.
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This archive was generated by hypermail 2b29 : Wed Aug 15 2001 - 21:00:33 EST