Re: error: invalid signature

[Andrei Borzenkov]

11.05.2016 20:42, Adrian пишет:
> hi,
> 
> I would like to make a chainboot from an usb key to the third hd with
> centOS. I installed grub2 at the usb key and created the grub2 file
> inside the usb key (/boot/grub2/)
> 
> grub.cfg:
> 
> menuentry 'centosOS hd3' {
>       chainloader (hd3,1)+1
> }
> 
> the booting ends with error: invalid signature. I tested some other
> combinations with: set root, search, filelocation, insmod,...
> 
> But every time the same message.
> 
> I have no idea what´s wrong or what the error mean.
> 

This means the first sector of this partition does not have 0xAA55 in
the last bytes. This is by convention used to indicate that sector
contains executable code.

> On third HD it´s CentOS7, first partition ext4 where the "/boot"
> directory is located. All the other partitions are lvm´s (/,/home, swap).
> 

All of this is irrelevant for chainloading. Chainloader simply loads one
sector and jumps to it. It has no idea about partitions, file systems or
LVM.

You have to either setup your CentOS so that it installs boot block into
this partition, or simply load CentOS kernel directly

menuentry "CentOS USB" {
  insmod ext2
  insmod part_msdos
  search --set --fs-uuid $UUID_OF_YOUR_CentOS_BOOT_PARTITION
  linux /boot/vmlinuz
  initrd /boot/initrd
}

Adjust kernel and initrd names as needed.

> Till this day, nobody has an answer or an idea what´s wrong. So you´re
> my last hope.
> 
> Sorry for my bad Englisch.
> 
> 
> Regards from the Black Forest / Germany
> 
> 
> 
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