2016-06-30 3:48 GMT+02:00 Bruce Dubbs <[email protected]>:
> thibaut noah wrote:
>
>
> Why would i do that? grub needs to have /boot in first position on the
>> disk?
>>
>
> That is not correct. The grub.cfg file specifies the /boot directory. For
> example 'set root (hd1,3)' would set the /boot directory as sdb3 assuming
> that /boot is a stand-alone partition.
>
>
> Not at all, i don't have ANY Physical disk, i have two virtual disks (said
>> it earlier) and what i do is creating another virtual machine with just
>> the
>> virtual drive of lfs
>> and i want to boot like this.
>>
>
> How is your second drive, sdb, partitioned? Does it use a GPT or MSDOS
> partition table. If GPT, it needs a separate bios_grub partition that is
> not formatted at all. Grub uses that as a raw partition when grub_install
> runs. /boot is separate. For an MSDOS partition table, the first
> partition should start at a 1MB boundary (not sector 63). Grub then
> installs its needed data in the unformatted region between the first sector
> and the first partition.
Gpt, i used cfdisk to partition it.
Damn :/
>
>
> * said grub will need to know what are the _real_ partitions on sda that
>>> '/' and '/boot' are on.
>>>
>>
> Not really. The only thing grub needs to know is where to find the
> kernel. Since it does not know where to find fstab, it has to be told with
> the set root command or the location of the kerenl has to be specified
> explicitly like:
>
> linux (hd1,3)/vmlinuz-version root=/dev/sda4
>
> The root= on the command line is the *kernel's* view of the disk layout.
> Grub's view is often different.
>
>
> Please note that my fstab and my grub file have been made with the
>>>> assumption that by having one disk only sdb would become sda on the new
>>>> virtual machine.
>>>>
>>>> fstab :
>>>> 1. /dev/sda1 / ext4 defaults 1 1
>>>> 2. /dev/sda2 swap swap pri=1 0 0
>>>> 3. /dev/sda3 /boot ext2 defaults 1 1
>>>> 4. proc /proc proc nosuid,noexec,nodev 0 0
>>>> 5. sysfs /sys sysfs nosuid,noexec,nodev 0 0
>>>> 6. devpts /dev/pts devpts gid=5,mode=620 0 0
>>>> 7. tmpfs /run tmpfs defaults 0 0
>>>> 8. devtmpfs /dev devtmpfs mode=0755,nosuid 0 0
>>>>
>>>
> Fine for an MSDOS partition table.
>
> grub.cfg :
>>>> 1. # Begin /boot/grub/grub.cfg
>>>> 2. set default=0
>>>> 3. set timeout=5
>>>> 4.
>>>> 5. insmod ext2
>>>> 6. set root=(hd0,3)
>>>> 7.
>>>> 8. menuentry "GNU/Linux, Linux 4.4.2-noah" {
>>>> 9. linux /vmlinuz-4.4.2-tnoah root=/dev/sda1 ro
>>>> 10. }
>>>>
>>>
> - Disk /dev/sdb: 15 GiB, 16106127360 bytes, 31457280 sectors
>>>> - Units: sectors of 1 * 512 = 512 bytes
>>>> - Sector size (logical/physical): 512 bytes / 512 bytes
>>>> - I/O size (minimum/optimal): 512 bytes / 512 bytes
>>>> - Disklabel type: gpt
>>>> - Disk identifier: F700B567-368F-4096-BB5B-6B2A5C670F10
>>>> -
>>>> - Device Start End Sectors Size Type
>>>> - /dev/sdb1 2048 20973567 20971520 10G Linux filesystem
>>>> - /dev/sdb2 20973568 29362175 8388608 4G Linux filesystem
>>>> - /dev/sdb3 29362176 31457246 2095071 1023M BIOS boot
>>>>
>>>
> This is your problem. It is inconsistent with the above. First, sdb3 is
> way bigger than it needs to be. 1M is recommended, not 1023. If you
> formatted it as ext2 then that is wrong. What I suggest is deleting
> /dev/sdb3 and creating a new 1M /dev/sdb3 and a new 100M /dev/sdb4 to be
> mounted as /boot. sdb3 needs to be of type BIOS Boot and sdb4 should be
> Linux filesystem. This is what I have:
>
>
There is a misunderstanding here, sdb3 appears as bios boot because i put
the flag there by following a tutorial on how to manage to install grub.
Sdb3 is my /boot partition with kernel and all installed on it.
But i get what you're saying, basically i need a dummy 1M empty partition.
> Device Start End Sectors Size Type
> /dev/sda1 2048 4095 2048 1M BIOS boot
> /dev/sda2 4096 395263 391168 191M Linux filesystem
> /dev/sda3 395264 39456767 39061504 18.6G Linux filesystem
>
> Where sda2 is /boot and sda3 is /
>
> If you make the changes to your system that I suggest, then grub.cfg needs
> to be changed to set root=(hd0,4) and change fstab device for /boot to
> sda4. Of course you will need to repopulate /boot with the kernel and
> rerun grub-install.
Makes more sens, thanks
>
>
> -- Bruce
>
>
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