grub4dos multiboot usb, some unresolved questions External links Options

[caze]

EDIT: as jaclaz advised, here comes a part collecting several questions of mine. this is also now a bit more ordered and probably clearer phrased. sorry for posting it first in a very awkward way.

This was splitted from here:
http://www.boot-land.net/forums/index.php?showtopic=6843
where I report a number of successes.

any help in the following issues i would very much appreciate. maybe the experts here can correct my understanding or tell me how to solve remaining issues. things i do not understand include:

1. does crossmapping (cd) help in some cases?
EDIT: what i mean is: you can map something on (hd32), (fd0) etc. can you also use (cd) and does this give any advantage?

2. partnew (hd0,3) 0x00 (hd0,0)/my_partition.img (being a contiguous partition image file) - when useful?
EDIT: according to jaclaz (below), seldomly useful and to be used with utmost care

3. working with custom ramdisk, (rd), "RAW=0, `int15/ah=87h' will be used to access memdrives. "map --ram-drive=RD" where RD default to 0x7F which is a floppy. If the RAM DRIVE is a hard drive image (with partition table in the first sector), you should set RD >= 0x80 and RD < 0xFF.. map --rd-base=ADDR. map --rd-size=SIZE. ADDR specifies the physical base address of the ramdisk image" ... examples, possible uses?
EDIT: some hints on this below from jaclaz with reference to section in GRUB4DOS README

EDIT: topic below rephrased - it was not even understandable before.
4. how to be able to use all of syslinux, grub4dos, bcdw, cdshell et al on one single unpartitioned usb stick? is it possible with grub4dos booting at first?

(these seem to have several advantages or disadvantages over each other. only syslinux and grub4dos seem to be able to start directly from usb. (there seem to be other new bootloaders which can do that but not have advantages over them both. maybe aero is an exception as it can chainload (?) isoemu, grub4dos, isolinux, bcdw.) now i took it that there are several freely available isos coming with isolinux. i thought if one had another bootmanager, esp. syslinux, in front of grub4dos (which can be loaded from almost anything), those isos could be handled easier. probably that is wrong as the problems after entering protected mode / leaving linux boot shell would remain. probably people have also tried to (chain?) load other bootmanagers from grub4dos. probably a custom boot.ini could be helpful here. at least, it seems that booting cdshell isos work very well from grub4dos directly. (see note above) from cdshell then, bcdw and syslinux isos should work. (untried) i suspect there could also be gained something from booting floppy images with another bootloader. maybe this would involve working on the bootsector, or the .sif-files of an iso. well, probably at least half of these illinformed expectations of mine are nonsense anyway.)

5. most problems remaining for me have to do with what to do if a booted iso/floppy won't find itself (e.g. complaining "insert root floppy", "vfs: unable to mount root on fs"). especially, i'd like to run avira rescue cd (does boot, but not start scanning) and gdata avk iso (boots, but then does not find itself).
EDIT: also, tomsrtbt, resque, rescue02, brd, banshee won't work for me until now (tried in several ways). any clues available for this?
EDIT: very helpful general explanations are given by ilko and jaclaz below.

6. could you please also tell me if it is always necessary to work on txtsetup->notsetup? (marked as (?) above)? thank you very much!

[was_jaclaz]

things i do not understand include:

1. - does crossmapping (cd) help in some cases?
2. - partnew (hd0,3) 0x00 (hd0,0)/my_partition.img (being a contiguous partition image file) - when useful?
3. - working with custom ramdisk, (rd), "RAW=0, `int15/ah=87h' will be used to access memdrives. "map --ram-drive=RD" where RD default to 0x7F which is a floppy. If the RAM DRIVE is a hard drive image (with partition table in the first sector), you should set RD >= 0x80 and RD < 0xFF.. map --rd-base=ADDR. map --rd-size=SIZE. ADDR specifies the physical base address of the ramdisk image" ... examples, possible uses?

1. Can you better explain what you mean by "crossmapping"? An example would help.
2. partnew is useful in a very small number of cases, namely when booting a Logical Volume inside Extended as if it were a Primary Partition - risky as it actually WRITES to the MBR - my personal advice is to leave it behind for the moment, however see here: http://www.boot-land.net/forums/index.php?showtopic=6348 and links within
3. an example is given in the grub4dos_readme.txt in the part "About the DOS utility `hmload' " it can be useful for DOS and some Linux builds, not (yet ) for NT based systems

what i plan to try next: use syslinux and start grub4dos from there and see if this helps in cases where grub4dos won't work. is it worth the time?

Cannot see the advantage of it, mainly because I am not sure to have understood what you plan to do with syslinux

most problems remaining for me have to do with what to do if a booted iso/floppy won't find itself (e.g. complaining "insert root floppy", "vfs: unable to mount root on fs"). especially, i'd like to run avira rescue cd (does boot, but not start scanning) and gdata avk iso (boots, but then does not find itself). any clues available for this?

Problem in this case is that the .iso or .floppy tries to re-access the device, which in the initial stage is "faked" by grub4dos, but later is nowhere to be found, modifications need to be made INSIDE the .iso or floppy.

jaclaz

[was_jaclaz]

1. is still missing an example

4. "YES", but actually 4. and 5. are different variations of the same question and "circle around" the same problem, grub4dos "fake" CD is only valid as long as "real mode" is used.

6. this also I cannot understand.:

now further stuff can be added to /menu.lst, like:

- windows xp pe version. can be built e.g. with pe builder or winbuilder or ubcd4win or reatogo etc. when finished, one gets /i386. copy contents to /minint on usb stick. rename resulting ntldr or setupldr.bin to /peldr on stick.
maybe (?) also necessary is: get gsar from http://gnuwin32.sourceforge.net/packages/gsar.htm.
copy or rename txtsetup.sif to notsetup.sif
gsar -b -o -sBT:x00:x00:x00\:x00:x00:x00txtsetup -rBT:x00:x00:x00\:x00:x00:x00notsetup peldr
(here are further nice to read instructions: http://www.msfn.org/board/SOLVED-Install-M...B-t114543.html)

Can you expand a bit on it?


jaclaz

[caze]

hmm. first let me say thank you for the help i already got from you. and for splitting the post.

i guess point 1 is probably too dumb to think further on it. i stumbled over this when i had even less understanding of these issues than now. i was unsure why all those iso emulation examples always work with (hd32) when there is also (cd). i only saw examples with (cd) in the style of "chainloader (cd) / boot". from the grub4dos readme i got the vague idea that (cd) was more connected to how the bios sees things and asked myself if points 4 and 5 could be solved by something like "map --mem /suchandsuch.iso (cd) / map --hook / chainloader (cd)[+1] / boot". but that seems nonsense.

i am beginning to see the point of the mingling of points 4 and 5, but have to think more on this. can you explain a bit more how one would go from grub4dos to syslinux directly? or does one have to patch together a custom bootdisk or iso image?

about 5. i am, for instance, still wondering why tomsrtbt and avira and gdata will not work for me. are there any ready-made solutions available?

in 6. my question is: is it always necessary to use gsar to change txtsetup->notsetup? or if not always, when? what is the exact use of this? (maybe you can give me a link to an helpful explanation somewhere)

maybe connected with this, maybe not:
7. i had some problems with ntosknrl.exe not found, but came around these somehow, however, without really knowing how. i also found no satisfying explanation, only that either the file really is missing or that somehow the whole setup is broken. probably you know a lot more than that about this error.

if you allow rather unrelated further questions:

8. how does one work with bcd to add custom vista versions?

9. is it possible to take a running normal xp installation and package it into a bootable image, e.g. by also patching the registry information about what harddrive it runs from? (i do not mean to copy it to a further partition - that could be relatively easy had)

10. what way would you recommend to emulate other systems from a (minimal) os booting from usb stick? i guess there could be a pe builder addon of qemu or vmware or virtualpc etc. or a minimal linux distro to which one could add such a software more or less "on the fly". i heard there is MoA but did not really understand what that is useful for. e.g. i still have a useful w98-vmware-image that i would like to get running after booting from stick in as few steps as possible. (one nice solution would be enough, of course)

again, thank you very much for your very helpful advices.

[was_jaclaz]

SOME answers.

5. I have no idea about what actually needs to be changed on "ANY" distro/iso/CD, all I can give you is some "general" explanation of how it works.
Let's take a "generic" "no name" Linux distro:
All it is needed to boot a "basic" Linux are two things:
the kernel
the initrd (initial ramdisk image)
In a typical grub4dos entry for a Linux from .iso:

CODE

title Some Linux flavour
find --set-root /linux.iso
map /linux.iso (hd32)
map --hook
root (hd32)
kernel /somedir/bzImage [linux options]
initrd /somedir/initrd

everything works, but once the kernel and initrd is loaded, it depends on WHERE the linux will look for other files.
If it looks on the CD, it won't find them, as the CD doesn't exist anymore, as the grub4dos "faking" has ended.
If it searches for them on drives, it won't find them, as above.
If there is some kind of searching for the other files, it may find them.
If among the [linux options] there is a path or something like that, just as an example:

CODE

iso_location=/boot/IMG/pmagic-svn.iso

it will work.
Same happens with an entry chainloading the whole .iso, like:

CODE

title Some Other Linux flavour
find --set-root /anotherlinux.iso
map /anotherlinux.iso (hd32)
map --hook
root (hd32)
chainloader (hd32)

if the .iso is "somehow" - don't ask me HOW - "self-contained", it will work, the Acronis is an example.

6. I have NO idea what is that useful for:
http://www.msfn.org/board/index.php?showto...14543&st=22

You may want to post on that thread and ask andy_le2k for clarifications.

7. ntosknrl.exe missing can be caused by a number of causes, cannot say without more details, basically, and strangely enough, "ntoskrnl.exe missing" actually means "ntoskrnl.exe missing", though it should be read more properly as:
"I cannot find ntoskrnl.exe where you told me to look for it, you are a jerk!"
(I like aggressive error messages)


8. This opens a completely new field.
Go here:
http://www.multibooters.co.uk/

This expresses nicely my past, current (and future) personal feelings regarding Vista:
http://www.msfn.org/board/index.php?showto...25258&st=12

9. NO, not until someone finds a way, right now the only way involves using RAMDISK booting (read MobileOS), read this to have an idea about what I'm talking about:
http://www.boot-land.net/forums/index.php?...c=5512&st=0
The "XP Kansas city shuffle" or "fake signature" method opens up new possibilities, but still ther is not yet a tested, working solution AFAIK.

10. MOA is a working solution, but uses VMWare.
You can boot Qemu from good ol' DOS with HX dos, but speed won't be good.
Most probably a very small Linux build running Qemu would be the most practical and compact solution, or a VERY basic PE, (read picoXP or similar derivatives or even XPCLI).
The "right" solution:
http://www.boot-land.net/forums/index.php?showtopic=4643
has not been found yet, again AFAIK.

jaclaz

[caze]

wow! that was incredibly helpful! thank you very very much. it will take me a lot of time to work myself through at least half of this...

(i am still very interested in this "selfcontained iso" stuff. if anyone could explain more about that, this would be also great.)