Re: [PATCH 2/7] release/combined: Compress installation image

Demi Marie Obenour
2025-11-02T19:38:37Z

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On 11/2/25 07:05, Alyssa Ross wrote:
> Demi Marie Obenour <demiobenour@gmail.com> writes:
>
>> On 11/1/25 18:15, Demi Marie Obenour wrote:
>>> On 10/29/25 12:51, Alyssa Ross wrote:
>>>> Alyssa Ross <hi@alyssa.is> writes:
>>>>
>>>>> Demi Marie Obenour <demiobenour@gmail.com> writes:
>>>>>
>>>>>> This will be needed once the B partitions are added. Otherwise,
>>>>>> tar2ext4's size limit is exceeded.
>>>>>>
>>>>>> The timeout is increased to account for the very slow compression
>>>>>> process.
>>>>>>
>>>>>> Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
>>>>>> ---
>>>>>> release/checks/integration/meson.build | 2 +-
>>>>>> release/combined/eosimages.nix | 14 +++++++++-----
>>>>>> 2 files changed, 10 insertions(+), 6 deletions(-)
>>>>>
>>>>> I haven't built this yet, so maybe I'm wrong somehow, but doesn't this
>>>>> break "Try Spectrum"? GRUB isn't going to be able to loopback mount a
>>>>> compressed image, I assume. That's why I keep asking what GNOME OS
>>>>> does. We currently produce an image that lets you install Spectrum, or
>>>>> try it out in a live image. Do they do that too? If so, how do they
>>>>> make it so that live image is bootable without being huge? Does their
>>>>> installer resize partitions, perhaps?
>>>>>
>>>>> (I reviewed the rest of the patch anyway, but I think we're going to
>>>>> need a different approach here.)
>>>>
>>>> Okay, I've finally got the answers I wanted about the GNOME OS installer
>>>> on Matrix. It sounds like it doesn't copy a whole disk image like
>>>> eos-installer does; rather it copies individual partition images using
>>>> systemd-repart. This means they can distribute small partition images,
>>>> and install them into partitions with room to grow, which would solve
>>>> this problem.
>>>>
>>>> Reusing GNOME OS's installer sounds like it would be good then, but I
>>>> don't know how much work it would be, and don't want to block this work
>>>> on that, so I suggest we go ahead with uncompressed, small partitions
>>>> for now — either sized to content or slightly bigger than content — and
>>>> then later on we switch to GNOME OS's installer, and then increase the
>>>> sizes of the installed partitions. Only at that point would we consider
>>>> Spectrum installs "stable".
>>>
>>> I agree in the long term, but I found a short-term workaround: use
>>> erofs instead of ext4. That compresses the giant runs of zeros down
>>> to almost nothing, and its mkfs tool doesn't have the same file size
>>> limitations. The only difficulty is that if we should have dm-verity
>>> protection in the installer for ext4, we _really_ ought to have it
>>> for erofs. That's a separate change, though.
>>
>> Actually, that doesn't work either. The installer doesn't find the
>> erofs image. I suspect this is a udisks bug but am not particularly
>> interested in fixing it, especially as this installer is going to
>> be replaced.
>>
>> Using small installation images also doesn't work. Even with very
>> little room to grow, the image is too big for mkfs.ext4 and tar2ext4
>> to handle.
>
> You mean that adding the B partitions makes the image too big?

This is correct. I tried for a day to find workarounds but without
success.
--
Sincerely,
Demi Marie Obenour (she/her/hers)

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