(solved)Re: how to use boot.img.gz

[Long Wind]

Thank Thomas Schmitt!

I can't use the file for that purpose.

I will try other methods.

On Tuesday, April 24, 2018, 5:16:13 PM GMT+8, Thomas Schmitt <scdb...@gmx.net> wrote:

Hi,

Long Wind wrote:
> /debian/dists/Debian9.4/main/installer-i386/current/images/hd-media
> it's in directory above

Do you mean something like
  http://ftp.debian.org/debian/dists/stretch/main/installer-i386/current/images/hd-media/
?

It seems hardly to be capable of doing anything without the files from
an installation ISO.
  https://www.debian.org/releases/stretch/i386/ch04s03.html.en#usb-copy-easy
says that you first put uncompressed hd-media/boot.img.gz onto an USB stick
(to get an unpartitioned 1 GB stick with FAT filesystem, bleh), then download
a netinst ISO and put it as file into the filesystem on the USB stick.

The strings in "/initrd.gz" look like it can find the ISO image and mount
it in order to use its files.
So the whole image seems to be a USB stick frontend to (small) i386 or amd64
installation ISOs, which meanwhile are ready for USB stick on their own.

> is it possible to create a bootable CD from it?

Rather not. if you mount it as FAT filesystem and look at its content,
there is not much more than a SYSLINUX bootloader, a Linux kernel "/linux",
and two initial ramdisks "/initrd.gz", "/initrdg.gz".

There is no file "isolinux.bin" and no EFI System Partition in boot.img.gz.
So there is no software for the first step of booting from CD, neither for
BIOS nor for EFI.
So even if the necessary files for the second stage of a SYSLINUX bootloader
are present, you'd still need to get ISOLINUX files ("isolinux.bin" and maybe
others) to bridge the gap between BIOS and the second stage of ISOLINUX or
SYSLINUX.

You could pick the missing files from the installation ISO, which you have
to download anyways. Its file /.disk/mkisofs would give you an idea how to
pack up all files as bootable ISO for CD.

But why build a new ISO when you already have downloaded a good one ?


Have a nice day :)

Thomas

[Brian]

On Tue 24 Apr 2018 at 09:37:05 +0000, Long Wind wrote:

> Thank Thomas Schmitt!

> I can't use the file for that purpose.I will try other methods.

>
>
> On Tuesday, April 24, 2018, 5:16:13 PM GMT+8, Thomas Schmitt <scdb...@gmx.net> wrote:

[Good explanation snipped]

> But why build a new ISO when you already have downloaded a good one ?

I don't think Thomas Schmitt was quite saying you cannot boot from USB
using boot.img.gz but querying why you should want to. Isohybrid images
were introduced to Debian in 2011. Prior to that, boot.img.gz was one
method to boot a netinst image from USB on a machine which did not have
a CD drive (say). There is no call for this method unless an isohybrid
image is not available or it doesn't work.

You really should say what you are trying to achieve.

--
Brian.

[Thomas Schmitt]

Hi,

i wrote:
> > But why build a new ISO when you already have downloaded a good one ?

Brian wrote:
> I don't think Thomas Schmitt was quite saying you cannot boot from USB
> using boot.img.gz but querying why you should want to.

I still wonder, but am too shy to ask directly.

[Brian]

There is no problem with 'zcat boot.img.gz > /dev/sdX' and copying
a netinst 9.3 image to a USB stick. Boots fine and locates the image.
Then I get the dreaded "No kernel modules found...mismatch...kernel
used by this version of the installer...kernel version available in
the archive". Hopefully, a 9.4 image would fix that.

--
Brian.

[Thomas Schmitt]

Hi,

Brian wrote:
> There is no problem with 'zcat boot.img.gz > /dev/sdX' and copying
> a netinst 9.3 image to a USB stick. Boots fine and locates the image.
> Then I get the dreaded "No kernel modules found...mismatch...kernel
> used by this version of the installer...kernel version available in
> the archive". Hopefully, a 9.4 image would fix that.

Smells like bit rot.

https://bugs.debian.org/cgi-bin/pkgreport.cgi?repeatmerged=no&src=debian-installer
yields
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=891964
"Unable to install Debian Buster from buster mini.iso"
Date: Sat, 3 Mar 2018 11:03:01 UTC
with
"No kernel modules were found. This probably is due to a mismatch between"

Does the 9.3 ISO work properly if not wrapped in boot.img ?
(I.e. copied directly to /dev/sdX by cp or dd.)

[Brian]

On Tue 24 Apr 2018 at 15:56:03 +0200, Thomas Schmitt wrote:

> Hi,
>
> Brian wrote:
> > There is no problem with 'zcat boot.img.gz > /dev/sdX' and copying
> > a netinst 9.3 image to a USB stick. Boots fine and locates the image.
> > Then I get the dreaded "No kernel modules found...mismatch...kernel
> > used by this version of the installer...kernel version available in
> > the archive". Hopefully, a 9.4 image would fix that.
>
> Smells like bit rot.

No such message with a 9.4 image. I think the kernels from boot.img.gz
and the installation image have to match.

> https://bugs.debian.org/cgi-bin/pkgreport.cgi?repeatmerged=no&src=debian-installer
> yields
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=891964
> "Unable to install Debian Buster from buster mini.iso"
> Date: Sat, 3 Mar 2018 11:03:01 UTC
> with
> "No kernel modules were found. This probably is due to a mismatch between"
>
> Does the 9.3 ISO work properly if not wrapped in boot.img ?
> (I.e. copied directly to /dev/sdX by cp or dd.)

No problem there.

--
Brian.