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Re: GRUB and boot partition

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  Re: GRUB and boot partition microsoft gaofei <wangziheng@outlook.com> - 2017-12-29 02:30 +0100
    Re: GRUB and boot partition deloptes <deloptes@gmail.com> - 2017-12-29 11:10 +0100
      Re: GRUB and boot partition Pascal Hambourg <pascal@plouf.fr.eu.org> - 2017-12-29 12:50 +0100
        Re: GRUB and boot partition Gary Dale <garydale@torfree.net> - 2017-12-29 23:30 +0100

#190435 — Re: GRUB and boot partition

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I'm thinking about a question ,how my hard disk admits so much data ? If /boot partition is encrypted , then how does my hard disk admit GRUB ?

sudo fdisk /dev/sda , and press o to create a DOS partition table . This software starts on sector 2048 by default . So how does the 2048 sectors admit GRUB to achieve encrypted /boot  ?

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#190440

microsoft gaofei wrote:

> I'm thinking about a question ,how my hard disk admits so much data ? If
> /boot partition is encrypted , then how does my hard disk admit GRUB ?
> 
> sudo fdisk /dev/sda , and press o to create a DOS partition table . This
> software starts on sector 2048 by default . So how does the 2048 sectors
> admit GRUB to achieve encrypted /boot  ?

you don't encrypt boot

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#190444

Le 29/12/2017 à 11:02, deloptes a écrit :
> microsoft gaofei wrote:
> 
>> I'm thinking about a question ,how my hard disk admits so much data ? If
>> /boot partition is encrypted , then how does my hard disk admit GRUB ?
>>
>> sudo fdisk /dev/sda , and press o to create a DOS partition table . This
>> software starts on sector 2048 by default . So how does the 2048 sectors
>> admit GRUB to achieve encrypted /boot  ?

FWIW, here is what I replied to the OP's private mail :

GRUB core image embeds all the required modules to read /boot/grub, 
including crypto modules when /boot/grub is encrypted.

2048 512-byte sectors is 1 MiB. GRUB BIOS core image does not need so 
much space. GRUB BIOS was developed at a time when partition alignment 
was based on "cylinders", so the first partition usually started at 
sector 63. GRUB BIOS core image was initially designed to fit in that 30 
KiB space. It has grown a bit over time and is sometimes slightly bigger 
than 30 KiB, but 1 MiB is still plenty of space.

A copy of GRUB BIOS core image is kept in /boot/grub/i386-pc/core.img, 
so you can see its size.

> you don't encrypt boot

Why not ?

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#190456

On 2017-12-29 06:46 AM, Pascal Hambourg wrote:
> Le 29/12/2017 à 11:02, deloptes a écrit :
>> microsoft gaofei wrote:
>>
>>> I'm thinking about a question ,how my hard disk admits so much data 
>>> ? If
>>> /boot partition is encrypted , then how does my hard disk admit GRUB ?
>>>
>>> sudo fdisk /dev/sda , and press o to create a DOS partition table . 
>>> This
>>> software starts on sector 2048 by default . So how does the 2048 
>>> sectors
>>> admit GRUB to achieve encrypted /boot  ?
>
> FWIW, here is what I replied to the OP's private mail :
>
> GRUB core image embeds all the required modules to read /boot/grub, 
> including crypto modules when /boot/grub is encrypted.
>
> 2048 512-byte sectors is 1 MiB. GRUB BIOS core image does not need so 
> much space. GRUB BIOS was developed at a time when partition alignment 
> was based on "cylinders", so the first partition usually started at 
> sector 63. GRUB BIOS core image was initially designed to fit in that 
> 30 KiB space. It has grown a bit over time and is sometimes slightly 
> bigger than 30 KiB, but 1 MiB is still plenty of space.
>
> A copy of GRUB BIOS core image is kept in /boot/grub/i386-pc/core.img, 
> so you can see its size.
>
>> you don't encrypt boot
>
> Why not ?
>
There's a lot of (not so) old information about /boot. I still have one 
machine with a separate /boot partition because when I first set it up, 
it was still required when using an mdadm RAID array.

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