Re: [PATCH 0/2] Add support to have multi-purpose builds into a single initramfs image

Hi Kairui,

On 14/05/21 2:40 pm, Kairui Song wrote:
> Hi Hari,
> 
> On Fri, May 14, 2021 at 4:57 AM Hari Bathini <[email protected]> wrote:
>>
>> With the addition of modules.d/99squash module, most of the files in
>> the initramfs image can now be squash'ed. While this saves space, this
>> can also be extended further to provide support for having different
>> initramfs images built into a single image, each squash'ed separately
>> & activated based on different boot scenarios.
>>
>> For that, introduce two dracut options. One, '--squash-input-images':
>> takes a space-separated list of input initramfs images to squash &
>> include in the initramfs image. Patch one adds this option.
>>
>> Two, '--squash-image-conditional': takes a script file that sets up
>> the appropriate squash image for every possible boot scenario. The
>> second patch introduces this option.
>>
>> ---
>>
>> Hari Bathini (2):
>>        dracut: add a new argument "--squash-input-images"
>>        dracut/99squash: make sqaush image setup flexible
>>
>>
>>   dracut.sh                                     | 26 +++++++-
>>   modules.d/99squash/module-setup.sh            | 17 ++++-
>>   .../99squash/setup-squash-conditional.sh      | 65 +++++++++++++++++++
>>   .../99squash/squash-image-conditional.sh      |  5 ++
>>   4 files changed, 109 insertions(+), 4 deletions(-)
>>   create mode 100755 modules.d/99squash/setup-squash-conditional.sh
>>   create mode 100755 modules.d/99squash/squash-image-conditional.sh
>>
>> --
>> 2.31.1
>>
> 
> There are some major refactoring of the dracut squash module, see:
> https://github.com/dracutdevs/dracut/pull/1088
> 
> With this refactor, now the whole initramfs is compressed in the
> squash image, no longer blended with the original initramfs.
> So the re-squash of the "input image content" in this series can be skipped.
> 
> I think at least the series needs a rebase.
> 
> And I think maybe we can make things easier and flexible here to just
> add an argument like a `--custom-init` (or any other name, I'm bad at
> naming things), to allow user to use a custom init process, dracut can
> just move the old `init` to something like `init.dracut`, and custom
> init can either `exec init.dracut`, or do custom init in its own way.
> 
> User can combine dracut's `--include` and new `--custom-init` to do
> things like this patch.
> 
> I know this patch series will benefit fadump, so use that as an
> example. The initarmfs can be generated with `dracut --custom-init
> /path/fadump-init.sh --include /path/fadump-squash.img ... <other
> args>`. fadump-init.sh here will judge if it's fadump boot, and
> switch_root into fadump-squash.img if it is, or `exec /init.dracut` if
> it's not. fadump-squash.img is just the image extracted from a normal
> kdump initramfs with `lsinitrd /path/initramfs-kdump.img
> squash-root.img` (after the squash refactor, the squash-root.img is a
> complete environment so it can be used directly).
> 
> And I also have another idea about this. Since linux's initramfs can
> be simply contacted together, user can just create it's own overlay
> initramfs and append into the original initramfs. The later appended
> initramfs content will just override the original, any custom
> modifications can be done that way, no need to rebuild the original
> initramfs. Still use fadump as an example, create a `fadump.img`,
> which contain three parts: a custom init, dracut's default init
> (extracted from the original initramfs), and fadump-squash.img
> (extracted from kdump initramfs). Then just `cat fadump.img >>
> original-initramfs.img`.
> 
> And perhaps you can use Github PR to submit patch updates? Most dracut
> related patches are processed using Github PR workflow.

Thanks for the review. I assumed code on kernel.org & github.com would 
be the same. I should have checked that.Naive on my part. Sorry!

I will rebase, work on you suggestions and submit a PR.

Thanks
Hari