[gentoo-user] gentoo livedvd kernel

[gentoo-user] gentoo livedvd kernel

[James]

Hello,

I want to take a closer look at the (amd64) kernel that is 
used on the latest gentoo livedvd. The easiest way 
is to copy the kernel, /usr/src/.config and the /usr/src/System.map
files to the dev box for closer examination.

Where do I find these?  On the livedvd itself or ????

If all I can do is copy the actual kernel off the livedvd,
I can use makeoldconfig to recover the .config settings
to the next (minor) version of the same kernel version?

Ideas?


curiously,
James

Re: [gentoo-user] gentoo livedvd kernel

[Neil Bothwick]

[-- Attachment #1: Type: text/plain, Size: 702 bytes --]

On Wed, 12 Nov 2014 17:02:19 +0000 (UTC), James wrote:

> I want to take a closer look at the (amd64) kernel that is 
> used on the latest gentoo livedvd. The easiest way 
> is to copy the kernel, /usr/src/.config and the /usr/src/System.map
> files to the dev box for closer examination.
> 
> Where do I find these?  On the livedvd itself or ????

You have (at least) three options:

1) Boot from the DVD and copy /proc/config.gz to a writeable device.

2) Copy the kernel from the DVD and use
   /usr/src/linux/scripts/extract-ikconfig to extract the config.

3) Something else I will think of right after pressing Send.


-- 
Neil Bothwick

The best antiques are old friends.

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

[gentoo-user] Re: gentoo livedvd kernel

[James]

Neil Bothwick <neil <at> digimed.co.uk> writes:


> > I want to take a closer look at the (amd64) kernel that is 

> You have (at least) three options:

> 1) Boot from the DVD and copy /proc/config.gz to a writeable device.

cool, this gets me the .config file.

> 2) Copy the kernel from the DVD and use
>    /usr/src/linux/scripts/extract-ikconfig to extract the config.

Ok, I'm not sure where the actual kernel binary is on the livedvd.
I really want that actual binary.


> 3) Something else I will think of right after pressing Send.

Yes, there is a slick way to do this, but I cannot remember and
google yields too many (worthless) links....

thx,
James

Re: [gentoo-user] Re: gentoo livedvd kernel

[Neil Bothwick]

[-- Attachment #1: Type: text/plain, Size: 897 bytes --]

On Wed, 12 Nov 2014 18:31:07 +0000 (UTC), James wrote:

> > 1) Boot from the DVD and copy /proc/config.gz to a
> > writeable device.  
> 
> cool, this gets me the .config file.
> 
> > 2) Copy the kernel from the DVD and use
> >    /usr/src/linux/scripts/extract-ikconfig to extract the config.  
> 
> Ok, I'm not sure where the actual kernel binary is on the livedvd.
> I really want that actual binary.

I thought you just wanted the config. If you look in the bootloader menu,
either from the menu itself or at its config file on the disc, you will
see the path to the kernel it is using.

If the live DVD uses GRUB, the config is at grub.cfg as usual. If it uses
isolinux it will be either /isolinux/isolinux.cfg or
/boot/isolinux.isolinux.cfg.


-- 
Neil Bothwick

If at first you don't succeed, you'll get a lot of free advice from
folks who didn't succeed either.

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [gentoo-user] Re: gentoo livedvd kernel

[Rich Freeman]

On Wed, Nov 12, 2014 at 1:50 PM, Neil Bothwick <neil@digimed.co.uk> wrote:
> On Wed, 12 Nov 2014 18:31:07 +0000 (UTC), James wrote:
>
>> > 1) Boot from the DVD and copy /proc/config.gz to a
>> > writeable device.
>>
>> cool, this gets me the .config file.
>>
>> > 2) Copy the kernel from the DVD and use
>> >    /usr/src/linux/scripts/extract-ikconfig to extract the config.
>>
>> Ok, I'm not sure where the actual kernel binary is on the livedvd.
>> I really want that actual binary.
>
> I thought you just wanted the config. If you look in the bootloader menu,
> either from the menu itself or at its config file on the disc, you will
> see the path to the kernel it is using.
>
> If the live DVD uses GRUB, the config is at grub.cfg as usual. If it uses
> isolinux it will be either /isolinux/isolinux.cfg or
> /boot/isolinux.isolinux.cfg.
>

Generally the kernel is the easiest thing to get off of one of those
LiveDVDs by just sticking the DVD in a drive and reading it (without
booting it).  Everything else on the DVD except for the kernel and
initramfs and bootloader tends to go in some big squashfs or the like.
However, the kernel has to be someplace the bootloader can read it,
and that usually means a vmlinuz or whatever on the root directory.

You could probably just use the same kernel on your own system, unless
it has an embedded command line or initramfs (I forget offhand how
overriding either of these works).  Most bootloaders tend to not
require these, but in some embedded situations you could run into
them.  Once upon a time the kernel had a BIOS boot sector in the first
512 bytes so you could just dd the kernel onto a disk and boot it
(there is still a stub that will tell you to bugger_off_msg if you do
that in arch/x86/boot/header.S).  (just a bit of trivial there)

--
Rich

[gentoo-user] Re: gentoo livedvd kernel

[James]

Rich Freeman <rich0 <at> gentoo.org> writes:


> Generally the kernel is the easiest thing to get off of one of those
> LiveDVDs by just sticking the DVD in a drive and reading it (without
> booting it).  Everything else on the DVD except for the kernel and
> initramfs and bootloader tends to go in some big squashfs or the like.
> However, the kernel has to be someplace the bootloader can read it,
> and that usually means a vmlinuz or whatever on the root directory.

Right now the (2) systems are booted up on media, so I cannot test this.
(later on I will).


> You could probably just use the same kernel on your own system, unless
> it has an embedded command line or initramfs (I forget offhand how
> overriding either of these works). 

Yes. scp is my favorite for this.... but I want to look at the actual
kernels that are used for bootup of a livedvd and the minimal, for
many reasons.   

> Most bootloaders tend to not
> require these, but in some embedded situations you could run into
> them.  Once upon a time the kernel had a BIOS boot sector in the first
> 512 bytes so you could just dd the kernel onto a disk and boot it
> (there is still a stub that will tell you to bugger_off_msg if you do
> that in arch/x86/boot/header.S).  (just a bit of trivial there)

Do tell more.

Now this would be most useful to me. If you recall (over 6 months ago)
I was (am) working on a setup where I can use all of the old systems,
drives, usb, and a plethora of embedded boards  to run variants
of embedded gentoo through minimal gentoo. I particularly got stuck
on how to quickly reinstall a system moving media around. If
I could just "dd" kernels/images around, I could keep many images/kernels on
a server and then boot--> chroot one of those aforementioned "test boxes"
and quickly and have a minimal old cpu test system online for hacking.  I
(temporarily) shelved that project to get clustering going with btrfs, ceph
and mesos+spark on gentoo. Naturally, I have bitten off
a wee_bit too much, but, life is good!

Likewise, meino was (is?) working on porting/hacking the
old venerable netconsole.c   [1] to some newer embedded boards. 
Many variants of netconsole.c have existed over the decades.....
I think running embedded/minimum gentoos via secure portal is kind of the
next step (for me) after figuring out a semantic for being about to use all
those old x86 and amd64 boxes for various testings of singular codes
and all sorts of custombuilt hardware across the net.  That way
folks could hack remotely without having to have the specific hardwware.
Developing virtually is great, but at some point you have torun
the codes on actual hardware. After x86 I'm going to support
a variety of arm boards (that run linux).

*SO* do tell me more......as I'm curious about your "dd" of kernels
and such.

> Rich

James

[1] http://lxr.free-electrons.com/source/drivers/net/netconsole.c

[gentoo-user] Re: gentoo livedvd kernel

[James]

Neil Bothwick <neil <at> digimed.co.uk> writes:


> > Ok, I'm not sure where the actual kernel binary is on the livedvd.
> > I really want that actual binary.

> I thought you just wanted the config. If you look in the bootloader menu,
> either from the menu itself or at its config file on the disc, you will
> see the path to the kernel it is using.

I'll have to wait until I boot up again to try this. Right now I have
one booted off a recent minimal cd andt the other off the amd64-livedvd
that was produced earlier this fall....

> If the live DVD uses GRUB, the config is at grub.cfg as usual. If it uses
> isolinux it will be either /isolinux/isolinux.cfg or
> /boot/isolinux.isolinux.cfg.

using my old buddy "find" on the minimal cd I found this
/usr/src/linux/vmlinux

and
/mnt/gentoo/usr/src/linux-3.13.6-gentoo/x86/boot/compressed/vmlinux 

vmlinux.bin and   vmlinux.bin.gz    (hopefully no typos).

On the lived dvd I found these with find:

./mnt/livecd/usr/src/linux-3.15.6-aufs-r1/arch/x86/boot/compressed/vmlinux
./mnt/livecd/usr/src/linux-3.15.6-aufs-r1/vmlinux
./usr/src/linux-3.15.6-aufs-r1/arch/x86/boot/compressed/vmlinux
./usr/src/linux-3.15.6-aufs-r1/vmlinux

(a pair of symlinks)

On neither is found an image or iso* in /boot or such.....
I guess the minimalcd and the livedvd use differnet semantics
for including the kernel and where it is written on the media.

Additionally, on the livedvd (last fall, amd64) the /boot/grub/menu.lst
when Irun "file menu.lst" tells me that:
"menu.lst" is a broken symbolic link to 'grub.conf'

curious...
James

Re: [gentoo-user] Re: gentoo livedvd kernel

[Neil Bothwick]

[-- Attachment #1: Type: text/plain, Size: 800 bytes --]

On Wed, 12 Nov 2014 22:22:09 +0000 (UTC), James wrote:

> > If the live DVD uses GRUB, the config is at grub.cfg as usual. If it
> > uses isolinux it will be either /isolinux/isolinux.cfg or
> > /boot/isolinux.isolinux.cfg.  
> 
> using my old buddy "find" on the minimal cd I found this
> /usr/src/linux/vmlinux

The kernel is a file on the DVD, not buried in the squashfs filesystem -
the kernel is needed to mount that filesystem. Given the limited number
of files on the DVD it quickest to send the lot to file.
  

% find  -type f -exec file {} + | grep kernel
./boot/memtest86:        Linux x86 kernel
./isolinux/gentoo:       Linux kernel x86 boot executable bzImage.....
./isolinux/kernels.msg:  ASCII text


-- 
Neil Bothwick

Top Oxymorons Number 39: Almost exactly

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

[gentoo-user] Re: gentoo livedvd kernel

[James]

Neil Bothwick <neil <at> digimed.co.uk> writes:


> The kernel is a file on the DVD, not buried in the squashfs filesystem -
> the kernel is needed to mount that filesystem. Given the limited number
> of files on the DVD it quickest to send the lot to file.

Once booted up, I find did not find a file with kernel as part of the
name on neither the minimalcd or livedvd. Usage of "vmlinux" was an
oversite on my part.

When I used "vmlinux" to qualify the find search, I found those previously
mentioned, on the booted up medias.  Like I told likeWahoa, I'll have to
check there  once I unmount the media. I guess I could download and isoimage
and pull it apart, or burn it to usb and look. For now, I've found something
sufficient. With what you and Rich have said, I also can  parse out
many different kernels to look at.


> % find  -type f -exec file {} + | grep kernel
> ./boot/memtest86:        Linux x86 kernel
> ./isolinux/gentoo:       Linux kernel x86 boot executable bzImage.....
> ./isolinux/kernels.msg:  ASCII text


thx,
James

Re: [gentoo-user] Re: gentoo livedvd kernel

[Neil Bothwick]

[-- Attachment #1: Type: text/plain, Size: 1599 bytes --]

On Thu, 13 Nov 2014 15:43:21 +0000 (UTC), James wrote:

> > The kernel is a file on the DVD, not buried in the squashfs
> > filesystem - the kernel is needed to mount that filesystem. Given the
> > limited number of files on the DVD it quickest to send the lot to
> > file.  
> 
> Once booted up, I find did not find a file with kernel as part of the
> name on neither the minimalcd or livedvd. Usage of "vmlinux" was an
> oversite on my part.

The kernel is just a file, it can be called anything. It is the contents
that are important, which is why I used file.

> When I used "vmlinux" to qualify the find search, I found those
> previously mentioned, on the booted up medias. Like I told likeWahoa,
> I'll have to check there  once I unmount the media. I guess I could
> download and isoimage and pull it apart, or burn it to usb and look.
> For now, I've found something sufficient. With what you and Rich have
> said, I also can  parse out many different kernels to look at.

Either mountthe DVD or loop mount the ISO image, which is what I did, to
browse its contents.
> 
> 
> > % find  -type f -exec file {} + | grep kernel
> > ./boot/memtest86:        Linux x86 kernel
> > ./isolinux/gentoo:       Linux kernel x86 boot executable bzImage.....
> > ./isolinux/kernels.msg:  ASCII text  

Or, as suggested previously, look at the bootloader config file, that
will tell you the location of the kernel.


-- 
Neil Bothwick

There was a young man from the border
Who had an attention disorder.
When he reached the last line
He would run out of time
And

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

[gentoo-user] Re: gentoo livedvd kernel

[James]

Neil Bothwick <neil <at> digimed.co.uk> writes:


> % find  -type f -exec file {} + | grep kernel
> ./boot/memtest86:        Linux x86 kernel
> ./isolinux/gentoo:       Linux kernel x86 boot executable bzImage.....
> ./isolinux/kernels.msg:  ASCII text
> 

OK  so I found this old iso a workstation:


livecd-amd64-installer-2008.0-r1.iso

# less livecd-amd64-installer-2008.0-r1.iso

lists:

Directory listing of /
        29 drwxr-xr-x   7 1032  100       2048 Jul  7 2008 [     29 02] . 
        29 drwxr-xr-x   7 1032  100       2048 Jul  7 2008 [     29 02] .. 
        33 drwxr-xr-x   3 1032  100       2048 Jun 11 2008 [     33 02] docs 
       100 -rw-r--r--   1    0    0   27381760 Jul  7 2008 [    100 00]
gentoo.efimg 
        30 drwxr-xr-x   3    0    0       2048 Jul  7 2008 [     30 02]
gentoo.efimg.mountPoint 
     13470 -rw-r--r--   1    0    0      21776 Jul  7 2008 [  13470 00]
Getting_Online.txt 
     13481 -rwx------   1    0    0  616603648 Jul  7 2008 [  13481 00]
image.squashfs 
        50 drwxr-xr-x   2 1009  100       4096 Jul  7 2008 [     50 02]
isolinux 
4294967280 -rw-r--r--   1    0    0          0 Jul  7 2008 [    -16 00] livecd 
    314557 -rw-r--r--   1    0    0       6666 Jul  7 2008 [ 314557 00]
README.txt 
        52 drwxr-xr-x   3 1032  100       2048 Jun 11 2008 [     52 02]
snapshots 
        42 drwxr-xr-x   6 1032  100       2048 Jun 11 2008 [     42 02] .svn 


the gentoo.efimg looks like a kernel binary....
I've got to muck around awhile on this


thx,
James

Re: [gentoo-user] Re: gentoo livedvd kernel

[Neil Bothwick]

[-- Attachment #1: Type: text/plain, Size: 877 bytes --]

On Thu, 13 Nov 2014 18:03:09 +0000 (UTC), James wrote:

> Neil Bothwick <neil <at> digimed.co.uk> writes:

> > % find  -type f -exec file {} + | grep kernel
> > ./boot/memtest86:        Linux x86 kernel
> > ./isolinux/gentoo:       Linux kernel x86 boot executable bzImage.....
> > ./isolinux/kernels.msg:  ASCII text
> > 
> 
> OK  so I found this old iso a workstation:
> 
> 
> livecd-amd64-installer-2008.0-r1.iso
> 
> # less livecd-amd64-installer-2008.0-r1.iso
> 
> lists:
> 
> Directory listing of /

> the gentoo.efimg looks like a kernel binary....
> I've got to muck around awhile on this

You can only know it it is by looking inside it, just mount the ISO and
run file on the contents, as above. That way you can find what IS rather
than what looks like a kernel.


-- 
Neil Bothwick

Hors d'oeuvres: 3 sandwiches cut into 40 pieces.

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [gentoo-user] Re: gentoo livedvd kernel

[Walter Dnes]

On Thu, Nov 13, 2014 at 06:03:09PM +0000, James wrote

> the gentoo.efimg looks like a kernel binary....
> I've got to muck around awhile on this

  ***IF*** the option is enabled in the kernel, you might have
/proc/config.gz and be able to run

zcat /proc/config.gz > myconfig.txt

  Note that multiple other compression options are possible.  If the
above line doesn't work, try...

ls /proc/config.*

..and see if you have anthing similar.  E.g. for config.bz2 use bzcat,
etc, etc.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: [gentoo-user] gentoo livedvd kernel

[James]

email <at> missionaccomplish.com <email <at> missionaccomplish.com> writes:

> 
> The livedvd kernel sources are in /etc/kernels which is where genkernel
puts them.

Likewhoa----


Just the .config file, not the actual kernel.