Re: [gentoo-user] Re: MBR & GPT dual compliant format

[james]

On 07/29/2016 09:27 AM, R0b0t1 wrote:

 >
 >
 >

I
OK, so I have finally switch my posting to this email. Gmane.org is dead 
for now (hence my delayed responses).

[1] https://lars.ingebrigtsen.no/2016/07/28/the-end-of-gmane/

So in one thread, I'm going to post to variety of recent posts; 
recreated since I have a new email address now anyways and just got it
setup with gentoo-user. (sorry if this makes the thread hard to follow.

 > Neil
 >  It's the ESP (EF00) that can be used as /boot, EF02 is a special
 > partition that should exist but not be used.

Agreed. The posted example partition tables (PT) were just an attempt
to motivate any respondant to post an actual (PT) presented by whatever
tool so I could actually see what I'm trying to drive to. Soon, later 
tonight or tomorrow, I'll post an actual attempt from recovered failures.

 > Tomh
 > The OP wants a partition scheme for both "standard" and efi firmware,
 > so he wants an EF02 (gdisk name) of 1MB and an EF00 (also gdisk name).


Yes, this is a key point.

 > The OP wanted the EF02 to be mounted as "/boot" so it has to be
 > larger than 100MB in order to accomodate multiple kernels (and
 > possibly initramfs "thingies" as they're sometimes called here).

 > It's the ESP (EF00) that can be used as /boot, EF02 is a
 > special partition that should exist but not be used.

OK, my problem is I do not know exactly what this looks like. I am
assuming I can do it all with gdisk (which is gptfdisk right)?

So this is just a starting point of what the PT & fstab cold look like

Number  Start   End     Size    Type     File system     Flags
  1      1049kB  211MB   210MB   primary  ext2            boot
  2      211MB   139GB   138GB   primary  linux-swap(v1)
  3      139GB   952GB   813GB   primary  ext4
  4      952GB   2000GB  1049GB  primary  ext4

corresponding fstab::

/dev/sda1   /boot        ext2    defaults,noatime     0 2
/dev/sda2   none         swap    sw		      0 0
/dev/sda3   /         	 ext4    defaults,noatime     0 1
/dev/sda4   /usr/local   ext4    defaults,noatime     0 1


 > David Haller
 > You'd have to get rid of one of those partitions (I'd say /boot).

OK, I was already thinking about placing /boot under '/' anyway, as
many of the stage-4 images I will be using in the auto-image installs
are commonly found as using just 2 partitions anyway ('/' and swap)

The '/usr/local' will be optional depending on disk size and available 
space to provide this third partition. /usr/local will not be needed for 
boot(strap) and can be mounted after the systems is up. So /boot
is part of / now.

 > Mick
 > It seems you did not use gdisk or a late version of parted to created
 > the partition table?  Modern partition tools align the logical and
 > physical sectors to 4096B.

Yep, I just 'dogged' the PT hoping someone would create and post what it
should look like, or copy/paste a correct example from somewhere. Sorry

 >> 1      1049kB  211MB   210MB   primary  ext2    boot

 > Instead of ext2 follow the guide for creating a FAT fs partition with
 > an EF00 partition type.
 > James should set the boot flag in the partition table for /dev/sda1
 > and mount it under /boot (or /boot/EFI) in fstab.

I'm going to do away with a separate /boot for now and 'boot' partition 
will be moved under /.

 > R0b0t1
 > > It seems you did not use gdisk or a late version of parted to
 > created the partition table?  Modern partition tools align the
 > logical and physical sectors to 4096B.

 > It can be changed. SSDs are best used with 512B sectors. But, err...

Well, proper alignment was automatically taken care of with newer tools?
That sort of perfromance issue is also critical. Eventuall, SSD and usb3
mmc and all sorts of other media will be used, depending on the embedded
board's supported interface mix that will work with the vendor's (board) 
bootstrap code to bring up linux.

 > The protective MBR can point to another one and you can select which
 > GPT partitions are in it. But that's getting into some rube goldberg
 > action.

Is this true if one is using grub-legacy?

While I'm at it (gentoo specific) what is the difference in 
sys-boot/grub-static (0.96-r1 to  0.97-r12) and sys-boot/grub (0.97-r16)
in slot zero?

I'm assuming that sys-boot/grub-2.02_beta2-r9++ is all grub-2 with 
current enhancements.


I do appreciate all the inputs, and appologize again for the 
transitioning emails, complicated by the demise of gmane.org (my fav 
reading/posting for gentoo-user).

I'm going to post back as soon as I get an actually 2T disk setup with
all of this advise, just to check what folks think and eventually with
the results of booting a variety of mbr systems (efi and newer embedded 
systems as they are purchased.)

I have a few SSD to experiment with now and may try some usb devices
after the spinning rust PT is happy.


James