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Re: Two SoC ideas (comments are welcome!)

From: Andrei E. Warkentin
Subject: Re: Two SoC ideas (comments are welcome!)
Date: Sat, 24 Mar 2007 15:14:54 -0500

Actually, even now a Multiboot kernel has to do way too much work in terms of memory initialization. The real problem is that GRUB only gives you the BIOS memory map and the lowmem/highmem, which means you need to figure out an  "in use" memory map for yourself, by seeing if any kernel modules are present, if any ELF section headers  + sections have been loaded, etc. 

It would be nicer if the memory map passed by GRUB was a bit more complete than listing generally-available memory. If I could find out which memory is used by GRUB structures, which memory is used to load my kernel (+ modules), that would be much better.

Andrei Evgenievich Warkentin
Cell: (+1) (847) 321-15-55

On 24.03.2007, at 8:35, colyli wrote:


Specify loading address for each multiboot module is not a perfect idea.
Which will make kernel does more work on memory initiation. BTW kernel's
loading address can be specified by multiboot header.

After all, this is my feedback, just for your information. Enjoy
hacking :-)


在 2007-03-24六的 20:26 +0800,Wei Shen写道:

I will appreciate the comments from anybody on my ideas.

To Colyli:

You are right. Their "modaddr value" can do the same as my "addr =
value". The  former told Grub to load all the rest modules starting
from address value ; while the later only specifies the current
module's loading address. However, modaddr can not set the loading
address of the kernel.


Wei Shen

        For the first idea, it is clear to me. I have no comment on
        For the second idea, I need more information. Can you explain
        more for 
        the limition of "modaddr value" command, and how can the
        limition to be
        broken out by the "addr = value" option ?


On 3/24/07, Wei Shen <address@hidden> wrote: 
        Thanks for your advice.

        On 3/24/07, colyli <address@hidden > wrote: 

                In grub command line, you can edit the configre (even
                mistaken), so
                maybe it will not be worth to add an edit in grub. 

        I do not mean the configure of Grub menu list, but the config
        files of the OS, like boot.ini of Windows and inittab of

                An option to set the start address for grub to load
                multiboot module is
                great. This option will make kernel guys (who use
                multiboot modules) to 
                initiate the kernel more easy. I remember a branch of
                grub for L4 kernel
                supports this option, maybe it can be a reference if
                you are interested

        I know this approach, however, instead of an option, they add
        a new command modaddr. A limitation is that all modules after
        the "modaddr value" will be loaded in succession to a
        overriding address below address value.

                Best regards.


                在 2007-03-23五的 23:46 +0800,Wei Shen

I have two ideas and wonder whether they are welcome
                as SoC projects. 

1) Simple file editing
I think it is useful to add file edit function to
                Grub. Thus, if a
config file which is required to boot the OS
                successfully is
mistakenly written, we can still correct it in Grub
                and need not to 
reboot from the floppy or cdrom just for the

I know it would greately increase the complexity of
                Grub to support a
writable file system. However, if file writing does
                not change the 
block number of a file, things are much simpler.
                Since most config
files are small (occupying only one block), I think
                the solution will

2) addr option for module command

Add nn option: "addr = value" to the module command.
                If the addr
option is specified, Grub will load the module to
                address value
instead of the default address.


Wei Shen
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