Good evening everyone! I have been working on this for sometime, but can't figure it out. I am simply trying to get the working bootcode of a bootloader installed on an attached media, but can't figure this out!!! I have tried grub legacy, lilo, and grub2... The host system has it's drive listed as /dev/sda* and the target attached media is listed as /dev/sdb* and is mounted to /mnt/target.
With grub legacy, I was attempting to work with another media (/dev/sdc*, /mnt/source) that already had it installed and tried dirty hacks like:
dd if=/mnt/source/boot/grub/stage1 of=/dev/sdb bs=446 count=1
dd if=/mnt/source/boot/grub/stage2 of=/dev/sdb bs=512 seek=1
This will actually boot into a grub interface where you can enter things like:
root (hd0,0)
setup (hd0)
I get no error messages, but grub will boot to garbage on the screen and then stop.
With lilo, I actually had the package installed and tried to setup (after creating a lilo.conf):
default=Test1
timeout=10
compact
prompt
lba32
backup=/mnt/target/boot/lilo/MBR.hda.990428
map=/mnt/target/boot/lilo/map
install=/mnt/target/boot/lilo/boot.b
image=/mnt/target/boot/vmlinuz
label=Test1
append="quiet ... settime"
initrd=/mnt/target/boot/ramdisks/working.gz
And then from the prompt execute the following:
$ lilo -C /mnt/target/boot/lilo/lilo.conf -b /dev/sdb
Warning: /dev/sdb is not on the first disk
Fatal: Sorry, don't know how to handle device 0x0701
With grub2, I tried something like:
grub-mkconfig -o /mnt/target/boot/grub/grub.cfg
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.11.0-12-generic
Found initrd image: /boot/initrd.img-3.11.0-12-generic
Found memtest86+ image: /boot/memtest86+.bin
No volume groups found
done
I couldn't even get the above to generate a grub.cfg correctly or in the right spot so I gave up on this one... The entries listed above are for the host system, not the target system.
I can provide any additional information that you guys need to help resolve this problem.
-UPDATE-
After working with the media a bit longer, I decided to run an 'fdisk -l' and was presented with the following info:
Partition 1 has different physical/logical beginnings (non-Linux?):
phys(0,32,33) logical(0,37,14)
Partition 1 has different physical/logical endings:
phys(62,53,55) logical(336,27,19)
I should also note that when I try to mount the partition I always get a message that states:
EXT4-fs (sdb1): couldn't mount as ext3 due to feature incompatibilities
Not sure if that is just specific to busybox, or if that is related to the fdisk output. Anyhow, I don't know if the fdisk info is indicating that there may be a problem with the disk geometry that could be causing all these bootloaders to not work.
First stage boot sector code for grub legacy is in "stage1", for grub(2) in "boot.img". Fist stage code contains the address of next stage to be loaded on same disk.
On some other disk the address of next stage to be loaded could be (and is maybe) different.
I think using chroot and grub-install would be a better way to go.
See Grub2/Installing.
As for disk/partition structure:
dd if=/mnt/source/boot/grub/stage2 of=/dev/sdb bs=512 seek=1
maybe has overwritten partition table in MBR of sdb.
Related
I am running Linux 4.14.149 built with Yocto Zeus (3.0.0). I am running a read only filesystem, and recently found an issue where my UID (/etc/machine-id)was getting changed every boot (a result of this question - https://superuser.com/questions/1668481/dhcpd-doesnt-issue-the-same-lease-after-reboot ).
I am trying to make that file a link to the user-data partition so it will persist across reboots. I have tried making the link as part of a base-files_%.bbappend which is the way I made the link for the hostname (which works). This is the contents of that file (/var/local is our user data partition with is mounted RW in the init script):
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
hostname = ""
machine-id = ""
do_install_append() {
ln -sfn /var/local/etc/hostname ${D}/${sysconfdir}/hostname
ln -sfn /var/local/etc/machine-id ${D}/${sysconfdir}/machine-id
}
But I am seeing the following error when I tried to build that:
Exception: bb.process.ExecutionError: Execution of '/home/gen-ccm-root/workdir/tools/poky/build-dev/tmp/work/mi_nhep-poky-linux-gnueabi/mi-dev/1.0-r0/temp/run.read_only_rootfs_hook.50286' failed with exit code 1:
touch: cannot touch '/home/gen-ccm-root/workdir/tools/poky/build-dev/tmp/work/mi_nhep-poky-linux-gnueabi/mi-dev/1.0-r0/rootfs/etc/machine-id': No such file or directory
WARNING: exit code 1 from a shell command.
It turns out there are two things that touch that file; the rootfs-postcommands.bbclass and the systemctl python script (found in meta/recipes-core/systemd/systemd-systemctl/systemctl), the former of which (I think) is causing the error. It is failing in the do_rootfs step.
What is the best way to create this link? If there is a choice, I would rather not modify Yocto sources if that is possible.
You can do this by defining your own rootfs post-command, and appending it to ROOTFS_POSTPROCESS_COMMAND so that it runs after Yocto's built-in read_only_rootfs_hook that creates the empty /etc/machine-id file using touch.
# setup-machine-id-symlink.bbclass
ROOTFS_POSTPROCESS_COMMAND += "install_machine_id_symlink ;"
install_machine_id_symlink () {
ln -sfn /var/local/etc/machine-id ${IMAGE_ROOTFS}/etc/machine-id
}
# your-image.bb
inherit setup-machine-id-symlink
The Image Generation docs have more detail on how postprocessing commands are applied during the build.
Note: You will need to ensure that your persistent partition is mounted early, so that reading /etc/machine-id doesn't result in a broken symlink.
Alternatively, use bind mounts:
You could also do this at runtime by installing a systemd service that runs early in the boot sequence and bind mounts your persistent machine-id over the blank one provided by Yocto in the rootfs.
Using a systemd service (rather than a bind mount entry in /etc/fstab) is necessary because you will need to ensure the persistent machine-id file actually exists before creating the bind mount. Though, you may be able to make use of tmpfiles.d to do that instead.
After first boot, when machine-id is generated, update bootargs U-Boot environment variable to include systemd.machine_id= in the kernel command line parameter.
An ID specified in this manner has higher priority and will be used instead of the ID stored in /etc/machine-id.
Is there a command for the apple terminal to brute force a wipe of everything including all partitions, master boot records, and data on a usb flash drive?
Just a little information about the situation:
I just got a stick from a friend which seems to be damaged but it isnt a physical defect. I guess he just removed the stick while formatting or so.
I already tried to repartition, reformat and erase the stick with the Mac Disc Utility and I tried to format it on windows. Nothing of it worked, so I decided to use terminal for it (im just getting used to terminal/bash, so im a complete newbie at this) and tried the commands (all with sudo and diskutil in front of them ofc) repairDisk, reformat, partitionDisk, eraseDisk or zeroDisk, but nothing worked. Im getting this error message now: Error: -69759: Securely erasing data to prevent recovery failed
Underlying error: 5: POSIX reports: Input/output error
So my final thought is now that I have to clean everything from this drive as it seems there is something broken on a very low level and i would assume that completely wiping it will result in my diskutil to install a complete new partition scheme and everything on the drive so it will eventually start working again..
Thank you all in advance!
Screenshots:
Try this in Terminal if you are CERTAIN it is disk3:
sudo dd if=/dev/zero of=/dev/rdisk3 bs=65536 count=1000
If it says the disk is busy, make it un-busy!
sudo diskutil unmountDisk /dev/disk3
First, check what disk# your usb is (to be certain) in a terminal:
sudo diskUtil list
then
sudo dd if=/dev/urandom of=/dev/<your_usb_disk_here> bs=1m
If you get busy error and/or if the usb is in use elsewhere, stop what you are doing there and unmount it first as Mark Setchell said
sudo diskutil unmountDisk /dev/<your_usb_disk_here>
If you get a funky name from using bootcamp assistant or something, and you cannot get dd or even Disk Utility to wipe it for some reason, like "permission" problem, use:
diskutil eraseVolume HFS+ NAME <your_usb_disk_here>
Note that the last arg is not e.g. /dev/disk2 , but just the last part, disk2
I need to mount a VHD file at grub2 command prompt.
I tries using "loopback" command as shown below:
grub > insmod ntfs
grub > insmod ntldr
grub > loopback loop (hd0,1)/test.vhd
grub > ls (loop)/
error: unknown filesystem
I tried both "static" and "dynamic" vhd and both VHD file had ntfs partitioned data.
I guess VHD files have some header data which makes the filesystem not recognizable after "loopback" mount. I am able to mount and access "iso" files using same set of commands.
Is my guess correct? If so, is there a way to overcome this issue?
Well, your guess is half right:
Whilst VHD supports a linear "fixed" storage model, which actually is just the raw data as it would be stored on a "real" hard drive, followed by a VHD footer, this is most probably not usually the case; VHD supports dynamically resizing images, which of course aren't linear internally, so you can't simply boot into that.
I was finally able to get the data from the loop mounted data with following change in the above pasted grub command.
grub > insmod ntfs
grub > loopback loop (hd0,1)/test.vhd
grub > ls (loop,1)/
The file "test.vhd" was a single partitioned VHD file.
NOTE: Only "fixed" or "static" model VHDs work. I could not get it working with "dynamic" VHD (as suggested by #Marcus Müller )
Thanks for the help. Hope this helps somebody.
To use VHD disks on grub2 need:
insmod part_msdos
insmod ntfs
loopback loop /point/where/disk.vhd tdisk=VHD
ls (loop,msdos1)/
Here is what I am trying to do: I need to know whenever a file is read or used by a tool (e.g. compiler). I use ls to get the last accessed time using the following command
ls -l --time=access -u --sort=time --time-style=+%H:%M:%S
or
stat "filename"
But my files access times are not getting updated, I figured its because of caching! please correct me if I am wrong. So my next step was how can I clear the cache, researching it I came across some variations of the following command:
sync && echo 3 | sudo tee /proc/sys/vm/drop_caches
The thing is even after I execute this command my file access time is not updated! My way of testing access time is by opening the file in gEdit or call gcc on my source file.
My setting: Ubunto 12.0.4 running on VMware, which is running on Win 7
Question: what am I missing or doing wrong that my access time is not being updated??
What you're observing is the change in the default mount option starting 2.6.30 in order to bring about filesystem performance improvement.
Quoting from man mount:
relatime
Update inode access times relative to modify or change time.
Access time is only updated if the previous access time was ear‐
lier than the current modify or change time. (Similar to noat‐
ime, but doesn't break mutt or other applications that need to
know if a file has been read since the last time it was modi‐
fied.)
Since Linux 2.6.30, the kernel defaults to the behavior provided
by this option (unless noatime was specified), and the stricta‐
time option is required to obtain traditional semantics. In
addition, since Linux 2.6.30, the file's last access time is
always updated if it is more than 1 day old.
(Also refer to this and this.) You might be looking for the following mount option:
strictatime
Allows to explicitly requesting full atime updates. This makes
it possible for kernel to defaults to relatime or noatime but
still allow userspace to override it. For more details about the
default system mount options see /proc/mounts.
I set the HOME variable in /etc/launchd.conf using the following line: setenv HOME /Users/student
Now the machine wont boot at startup. I tried holding shift at startup but safe mode doesn't seem to be working. I tried holding cmd+s on startup and got into single user mode. I was able to bring up the /etc/launchd.conf file but I can not save/overwrite the existing file due to permission issues.
Is there some way to reset this file from single user mode or other to fix this? I'm open to other approaches as well. I am not a unix/linux power user by any means, fyi :)
Thank you in advance.
I'll give you two options, but first a warning: both of these involve using the command line to undo the damage, and if you do it wrong there's a possibility you'll make it even worse. A backup would've been a good idea, but it's a little late for that (well, actually, there are still ways to do it, but they also involve a risk of getting it wrong...). So whatever your do, be careful.
Option 1: use single-user mode (Command-S at startup). This will leave you running as root, which means you are not subject to normal file permissions; after remounting the startup disk for write access (mount -uw /) you should not get permissions errors. You said this didn't work; the most likely thing is that you mistyped the command (I see this happen a lot -- people either leave out the "/", or the space between "-uw" and "/"). Hint: if the mount command prints anything (other than the prompt for the next command) you typed it wrong. If that still doesn't do it, check the file's flags and metadata with ls -leO# /etc/launchd.conf and report the results.
Option 2: use recovery mode (Command-R at startup). This boots from a small hidden partition with a minimal copy of OS X. In recovery mode, pull down the Utilities menu and choose Terminal. This is actually a fair bit like single-user mode, except that the normal startup disk won't be /, it'll be /Volumes/Macintosh HD (or whatever it's named), and it'll already be mounted for write access. Since there's (probably) a space in the volume name, you'll have to quote or escape it:
$ cd "/Volumes/Macintosh HD"
$ mv launchd.conf launchd.conf-disabled