[oi-dev] GPT Partitioning for Illumos/Solaris

[Atiq Rahman]

Hi Toomas,
Gotcha, the 8MB partition is still needed for historical reasons.

Best!

Atiq

On Sun, Aug 17, 2025 at 3:06 AM Toomas Soome via oi-dev <
oi-dev at openindiana.org> wrote:

>
>
> On 17. Aug 2025, at 04:43, Atiq Rahman <atiqcx at gmail.com> wrote:
>
> Hi Eric,
> > The "Solaris Root" partition type is relevant to UFS, not ZFS. On UEFI,
> set s0/p1 to be an ESP, "boot, hidden, esp" flags and format it fat32
>
> Yep, I have done that quite a while ago. Linux is booting alright with
> that.
>
> > your "Solaris Reserved" should be s8/p9, 8Mib, -1MiB from end of disk
> . That's for legacy / MBR partitions. Mine is GPT. I don't need that or
> any other partition for Solaris. I only need one single partition of zfs /
> illumos and that's working so far.
>
>
> It is created automatically on GPT and it is used to store fabricated disk
> identifier for case the disk does not provide one for itself. It is
> originating from Solaris and since illumos is fork of Solaris, it is still
> there. MBR+VTOC setup is using space from ‘alternates’ for the same purpose.
>
> rgds,
> toomas
>
>
> On Thu, Aug 14, 2025 at 8:25 PM Eric J Bowman <mellowmutt at zoho.com> wrote:
>
>> >
>> > parted > mkpart illumos 767GB 100%
>> >
>> > and then set the partition type to solaris launching,
>> >
>> > $ sudo gdisk /dev/nvme0n1
>> >
>> > (set the GUID to "6A85CF4D-1DD2-11B2-99A6-080020736631" )
>> >
>>
>>
>> The "Solaris Root" partition type is relevant to UFS, not ZFS. On UEFI,
>> set s0/p1 to be an ESP, "boot, hidden, esp" flags and format it fat32, your
>> "Solaris Reserved" should be s8/p9, 8Mib, -1MiB from end of disk. Your ZFS
>> partition should be set to ZFS for illumos, FreeBSD ZFS for freebsd. Being
>> bootable is a property of the ZFS filesystem, not its partition.
>>
>> /EFI
>> /EFI/OpenIndiana/bootx64.efi (copy of loader.efi)
>> /EFI/boot
>>
>> I put rEFInd Plus in /EFI/boot, with a backup of its bootx64.efi in case
>> it gets overwritten.
>>
>> /EFI/boot/drivers/x64_zfs.efi
>>
>> This driver will allow rEFInd to stub-load loader64.efi from your ZFS
>> partition on most firmware, some will still need the
>> /EFI/OpenIndiana/bootx64.efi. I don't know if the string "OpenIndiana" is
>> registered, this one is:
>>
>> /EFI/FreeBSD
>>
>> That's the gist of multiboot on UEFI, more work if you want more than one
>> illumos or freebsd partition, but they will coexist peacefully.
>>
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