Re: [PATCH v2 10/10] meta-isar/canned-wks: Remove /boot mountpoint

[Henning Schild <henning.schild@siemens.com>]

On Sat, 5 Sep 2020 09:06:08 -0700 (PDT)
"vijaikumar....@gmail.com" <vijaikumar.kanagarajan@gmail.com> wrote:

> On Saturday, September 5, 2020 at 2:28:17 PM UTC+5:30 Henning Schild
> wrote:
> 
> > Hi, 
> >
> > i do not like this one at all. Suggesting people to hide the boot 
> > partition from debian as hard as they can? If i understand it
> > correctly. 
> 
> AFAIU , /boot mount-point[1] is wrong and is not needed without 
> --exclude-path of /boot in rootfs partition. 
> This optional mount-point serves only one purpose, i.e, to have an
> entry added in fstab or not by wic.
> We were okay with saying this EFI/bootloader partition mount-point as 
> /boot, since older wic
> was not adding the /boot mount-point to fstab.
> With this commit [2] in OE this is no longer the case.
> /boot is added to fstab and at boot the system would try to mount to
> this efi partiton to /boot
> directory which, if successful, will make the kernel, initrd and
> config files which were already available in /boot
> of rootfs unavailable when the system is booted. I donot see
> --exclude-path for /boot in the wks file,
> so this would just be wrong to have a mount-point like this. 

Not sure i get all that, but to me it seems we need a wks file without
boot or we need one with boot and the exclude. The exclude might not be
needed on OE, on debian it is ... so adding the exclude could be a
better default/example than removing the boot partition.

> [1] 
> https://github.com/ilbers/isar/blob/a0d6de4ac7dfb926b38cfcd44f2bc8852f2e43e3/meta-isar/scripts/lib/wic/canned-wks/sdimage-efi.wks#L5
> [2]
> https://github.com/openembedded/openembedded-core/commit/2376b05512ddb8c4ec3aaf1df11071f536a76bd9
> 
> 
> > In fact the hiding is an issue that should be solved, debian should 
> > know about that partition and use it correctly. 
> >
> > On EFI it only contains the bootloader, so such isar images will be 
> > able to receive kernel updates with apt-get during their lifetime.
> > They will never be able to update the bootloader, but that might be
> > ok. 
> >
> > On BIOS the story is different. These systems have the kernel in
> > the roots/boot only that kernel is never used for booting and the
> > machines will never be able to update the kernel they boot. 
> >
> > I always wanted to solve that but it was not too easy. The first
> > idea was just bootloader in the boot partition, like efi. But
> > syslinux can not boot files from other partitions, so we need the
> > kernel and initrd there. 
> > But now with the exclude feature it might be easier. Place the 
> > bootloader and config into rootfs/boot and point to the kernel
> > initrd symlinks in the config. (Done in our custom BIOS plugin) 
> > And now take rootfs/boot as boot, excluding it from rootfs.  
> 
> 
> Can you point me to some code where these kind of scenarios are? I
> assume these are all downstream? For downstream you could customize
> the wks with neccessary /boot as mountpoint for EFI and
> "--exclude-path /boot" to achieve
> what you want. I donot see the issue in removing it here.

There is no code to point to. What i described is the current state of
Isar and a possible direction it could take to fix the fact that the
boot partition is never visible in the running system. An issue
especially problematic for BIOS boot, since kernel updating is broken.

Just build a BIOS booting qemu (conf/machine/qemui386.conf), and install
i.e. linux-image-rt in the running system with apt-get

I am not saying this should not be merged. But this is a good time to
look at the "debians do not know about that boot partition" issue
again, instead of possibly making it worse and including bad examples
into meta-isar ... which will later end up in other layers.

Henning

> 
> >
> > Henning 
> >
> > On Thu, 3 Sep 2020 00:32:47 +0530 
> > Vijai Kumar K <Vijaikumar_...@mentor.com> wrote: 
> >  
> > > In the older version of wic, the fstab entry for /boot mountpoint 
> > > was skipped. 
> > > However in the latest wic this is not the case. Adding a /boot 
> > > mountpoint in part results in creating a fstab entry for
> > > automount. Remove it to avoid the unwanted mount which makes
> > > original contents unavailable in debian rootfilesystem. 
> > > 
> > > Signed-off-by: Vijai Kumar K <Vijaikumar_...@mentor.com> 
> > > --- 
> > > RECIPE-API-CHANGELOG.md | 17 
> > > +++++++++++++++++ .../lib/wic/canned-wks/common-isar.wks.inc | 
> > > 2 +- meta-isar/scripts/lib/wic/canned-wks/hikey.wks | 2 +- 
> > > .../scripts/lib/wic/canned-wks/sdimage-efi.wks | 2 +- 
> > > 4 files changed, 20 insertions(+), 3 deletions(-) 
> > > 
> > > diff --git a/RECIPE-API-CHANGELOG.md b/RECIPE-API-CHANGELOG.md 
> > > index 1839770..070cde3 100644 
> > > --- a/RECIPE-API-CHANGELOG.md 
> > > +++ b/RECIPE-API-CHANGELOG.md 
> > > @@ -246,3 +246,20 @@ by setting DEBIAN_BUILD_DEPENDS. 
> > > 
> > > ${S} can now be used for checking out sources without being
> > > linked implicitly with ${D} which needs to be filled explicitly
> > > in do_install as before. + 
> > > +### Wic adds /boot mountpoint to fstab 
> > > + 
> > > +With the latest wic, /boot mount point, if any, is added to 
> > > /etc/fstab. Debian +uses /boot to store the kernel and initrd
> > > images. If an image's wks file +specifies /boot mountpoint for
> > > boot partitions like EFI, the image may fail to +boot or might
> > > make the original contents of /boot unavailable after boot. +All
> > > unwanted /boot mountpoints should be removed. +   
> >  
> 
> Maybe I can add a bit more to
> this sentence to make it clear, something like unless you know what
> you are doing.
> I could add the rest of the wks entry below to highlight that /boot
> is not excluded in the first place.
>  
> 
> > > +Below is an example wks entry that might cause an issue.   
> 
> > +```   
> > > +part /boot --source bootimg-efi-isar --sourceparams 
> > > "loader=grub-efi" --ondisk sda --label efi --part-type EF00
> > > --align 1024 +``` +Drop the /boot entry to avoid issues. 
> > > +``` 
> > > +part --source bootimg-efi-isar --sourceparams "loader=grub-efi" 
> > > --ondisk sda --label efi --part-type EF00 --align 1024 +``` 
> > > diff --git
> > > a/meta-isar/scripts/lib/wic/canned-wks/common-isar.wks.inc
> > > b/meta-isar/scripts/lib/wic/canned-wks/common-isar.wks.inc index
> > > c8ea4c2..e7dabd4 100644 ---
> > > a/meta-isar/scripts/lib/wic/canned-wks/common-isar.wks.inc +++
> > > b/meta-isar/scripts/lib/wic/canned-wks/common-isar.wks.inc @@
> > > -1,3 +1,3 @@ # This file is included into 3 canned wks files from
> > > this directory -part /boot --source bootimg-pcbios-isar --ondisk
> > > sda --label boot --active --align 1024 +part --source
> > > bootimg-pcbios-isar --ondisk sda --label boot --active --align
> > > 1024 part / --source rootfs --ondisk sda --fstype=ext4 --label
> > > platform --align 1024 diff --git
> > > a/meta-isar/scripts/lib/wic/canned-wks/hikey.wks
> > > b/meta-isar/scripts/lib/wic/canned-wks/hikey.wks index
> > > 1e82f8c..840858e 100644 ---
> > > a/meta-isar/scripts/lib/wic/canned-wks/hikey.wks +++
> > > b/meta-isar/scripts/lib/wic/canned-wks/hikey.wks @@ -3,7 +3,7 @@
> > > # # SPDX-License-Identifier: MIT 
> > > 
> > > -part /boot --source bootimg-efi-isar --sourceparams 
> > > "loader=grub-efi" --ondisk mmcblk1 --label efi --part-type EF00 
> > > --align 1024 +part --source bootimg-efi-isar --sourceparams 
> > > "loader=grub-efi" --ondisk mmcblk1 --label efi --part-type EF00 
> > > --align 1024 part / --source rootfs --ondisk mmcblk1 --fstype
> > > ext4 --label platform --align 1024 --use-uuid diff --git 
> > > a/meta-isar/scripts/lib/wic/canned-wks/sdimage-efi.wks 
> > > b/meta-isar/scripts/lib/wic/canned-wks/sdimage-efi.wks index 
> > > 2afa016..e0fa7a1 100644 --- 
> > > a/meta-isar/scripts/lib/wic/canned-wks/sdimage-efi.wks +++ 
> > > b/meta-isar/scripts/lib/wic/canned-wks/sdimage-efi.wks @@ -2,7
> > > +2,7 @@ # long-description: Creates a partitioned EFI disk image
> > > without any swap that # the user can directly dd to boot media. 
> > > -part /boot --source bootimg-efi-isar --sourceparams 
> > > "loader=grub-efi" --ondisk sda --label efi --part-type EF00
> > > --align 1024 +part --source bootimg-efi-isar --sourceparams
> > > "loader=grub-efi" --ondisk sda --label efi --part-type EF00
> > > --align 1024 part / --source rootfs --ondisk sda --fstype ext4
> > > --label platform --align 1024 --use-uuid   
> >
> >  
>