[9fans] GPT partitions

[9fans] GPT partitions

[Jens Staal]

Dear all,

I am interested in moving from running Plan9 in a VM to (try to) running on
bare metal but since I am on a laptop with a single HDD and I play around with
a couple of different things, I need to use GPT instead of MBR to avoid the
silly 4 partition limit (since Plan9 can not be on an extended partition).

Does any of the Plan9 variants support booting from a GPT partition nowadays?
I have not experimented with EFI boot yet on my primary OS but as far as I
have read, this could also avoid chainloading bootloaders - any experience
with this?

I am also interested in the 64-bit HDD image from 9atom, but was never able to
load that one with syslinux - so if anyone got any tips and tricks there that
would also be cool.

Re: [9fans] GPT partitions

[erik quanstrom]

> Does any of the Plan9 variants support booting from a GPT partition nowadays?
> I have not experimented with EFI boot yet on my primary OS but as far as I
> have read, this could also avoid chainloading bootloaders - any experience
> with this?
>
> I am also interested in the 64-bit HDD image from 9atom, but was never able to
> load that one with syslinux - so if anyone got any tips and tricks there that
> would also be cool.

9atom has the beginnings of gpt support, but that is stalled.  the 9atom 64-bit
kernel needs *e820 set in the config area in the format
	*e820=memtype begin end ...
the easiest way to arrange this is to use iplfat or iplpxe.

there is no hdd image, there is a usb installer (image).  if you boot it from a hard drive,
then edit plan9.ini to reflect the drive its booting from.

good luck.

- erik

Re: [9fans] GPT partitions

[cinap_lenrek]

9front pc and pc64 kernels can be loaded by multiboot loader like grub (thanks
to aiju). plan9.ini can be passed as a module. it uses the multiboot memory map
as well. theres no program to read in the gpt partition table yet but that should
be easy. all you need is a small program to parse the gpt and write text to /dev/sdXX/ctl.

--
cinap

Re: [9fans] GPT partitions

[erik quanstrom]

On Fri Apr 25 11:52:48 EDT 2014, cinap_lenrek@felloff.net wrote:
> 9front pc and pc64 kernels can be loaded by multiboot loader like grub (thanks
> to aiju). plan9.ini can be passed as a module. it uses the multiboot memory map
> as well. theres no program to read in the gpt partition table yet but that should
> be easy. all you need is a small program to parse the gpt and write text to /dev/sdXX/ctl.

*all* the pc kernels, except for the nix kernel, do multiboot.  i removed
multiboot from nix. it's just so ugly.  perhaps a bad decision.  but there
is sadly a tradeoff between taste and compatability.

- erik

Re: [9fans] GPT partitions

[cinap_lenrek]

there was a multiboot header there but it didnt work. the problem is that multiboot
loader doesnt align the data segment of the kernel image to page size. the kernel
needs to move the data segment early before entering main().

--
cinap

Re: [9fans] GPT partitions

[erik quanstrom]

On Fri Apr 25 12:12:05 EDT 2014, cinap_lenrek@felloff.net wrote:
> there was a multiboot header there but it didnt work. the problem is that multiboot
> loader doesnt align the data segment of the kernel image to page size. the kernel
> needs to move the data segment early before entering main().

i wasn't unjustified in claiming multiboot is ugly.

- erik

Re: [9fans] GPT partitions

[Daryl M]

Jens,

I am currently working on a UEFI boot loader for Plan9.
The initial version will be 32-bit but should be followed shortly by an x64
(64 bit) version.

I'm hoping to be able to switch automatically between MBR and GPT schemes.

The Plan9 kernel appears to make many assumptions about its environment.
	(emphasis on "appears".  This changes as my knowledge increases)
The documentation in this area is also sadly lacking.

I'm slowly tracking down these issues and resolving them.

I don't have any idea when I will be done since I don't have lots of time to
work on it.

Daryl

-----Original Message-----
From: 9fans-bounces@9fans.net [mailto:9fans-bounces@9fans.net] On Behalf Of
9fans-request@9fans.net
Sent: Friday, April 25, 2014 5:00 AM
To: 9fans@9fans.net
Subject: 9fans Digest, Vol 120, Issue 38

From: Jens Staal
Subject: [9fans] GPT partitions

Dear all,

I am interested in moving from running Plan9 in a VM to (try to) running on
bare metal but since I am on a laptop with a single HDD and I play around
with a couple of different things, I need to use GPT instead of MBR to avoid
the silly 4 partition limit (since Plan9 can not be on an extended
partition).

Does any of the Plan9 variants support booting from a GPT partition
nowadays?
I have not experimented with EFI boot yet on my primary OS but as far as I
have read, this could also avoid chainloading bootloaders - any experience
with this?

I am also interested in the 64-bit HDD image from 9atom, but was never able
to load that one with syslinux - so if anyone got any tips and tricks there
that would also be cool.

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