From: "Stefano Babic" <email@example.com>
To: Mike Looijmans <firstname.lastname@example.org>,
Stefano Babic <email@example.com>,
Patches and discussions about the oe-core layer
Subject: Re: [OE-core] Build the "boot" partition image (just like the rootfs)
Date: Mon, 15 Mar 2021 15:58:35 +0100 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
On 15.03.21 15:46, Mike Looijmans wrote:
> Met vriendelijke groet / kind regards,
> Mike Looijmans
> System Expert
> TOPIC Embedded Products B.V.
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> Please consider the environment before printing this e-mail
> On 15-03-2021 14:47, Stefano Babic wrote:
>> Hi Mike,
>> On 15.03.21 14:13, Mike Looijmans wrote:
>>> For software updates, I want to have what would have gone into the
>>> boot partition of the WIC image as a separate file.
>>> If I want to have the contents of the rootfs as an ext4 image, I can
>>> just specify IMAGE_TYPES="ext4" in my image recipe.
>>> > This image I can feed to SWUdate and write to the rootfs storage.
>>> But I also want to be able to update the boot partition (for example,
>>> the raspberrypi has the annoying property that devicetree and kernel
>>> reside here).
>> This is very annoying, but you could also get rid of it. You can
>> install kernel and device tree in your rootfs (then they are located
>> in /boot as usual), and you switch to U-Boot ( RPI_USE_U_BOOT = "1").
>> The proprietary bootloader will start U-Boot instead of kernel, and in
>> u-boot you can load kernel and device tree from your rootfs.
> That's what I did on other boards, but for the RPi that's not enough.
> There's also firmware there, which interacts with the kernel, and the
> firmware is altering the devicetree too. It's pretty likely that the
> firmware needs an update too when the kernel gets a big update.
>>> If I create a WIC image, the boot partition is in there with the
>>> proper files (from IMAGE_BOOT_FILES) so I would really like to re-use
>>> that code. I could create the wic image and then cut out the part I
>>> want, but that doesn't seem particularly nice.
>> You can add vfat support for IMAGE_FSTYPES, and then you can build an
>> image (you can just take the files you have in IMAGE_BOOT_FILES).
> But that's *exactly* my problem: How do I get these IMAGE_BOOT_FILES
> into an image of sorts? Just setting IMAGE_FSTYPE="vfat" will put the
> rootfs contents in there, not the bootfiles I'm after.
rpi-bootfiles inherit nopackage, so you should write a recipe that
instead of simply deploying the files as this recipe does, install them.
You should then install it into /, as this is where they are put on the
VFAT partition. If they are in the package, you can write an image
recipe to install it via IMAGE_INSTALL, and via post process command you
drop what is not necessary (/etc,...).
Anyway, as far as I know, an IMAGE_FSTYPES += "vfat" is not supported,
you have also to add support for it.
>>> What I want to do at update time is to write the new boot partition
>>> to another location on disk, and then adjust the partition table to
>>> make the first partition entry point to the new copy. That way, in
>>> case of unexpected failure (power loss for example), the device
>>> remains bootable.
>> This does not seem to be atomic. It remains the risk that partition
>> table gets corrupted and then even the first bootloader cannot run. If
>> you want to have a power-cut safe way to update is not enough.
> It's not perfect but it's close enough. The partition table resides in a
> single sector, so chances of power-out at exactly this moment are small
> enough that I'm willing to take my chances here.
> My experience is that there's more chance of the SD card completely
> dying because of power-out during some internal mumbojumbo than
> corrupting that partition table.
True, that is. So simply the hardware does not allow a safe update,
point. Fully agree. Or use a very expensive industrial grade SD, but any
board with eMMC is then cheaper.
> Against that SD failure there's nothing
> I can do...
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next prev parent reply other threads:[~2021-03-15 14:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <email@example.com>
[not found] ` <firstname.lastname@example.org>
2021-03-15 13:13 ` Build the "boot" partition image (just like the rootfs) Mike Looijmans
2021-03-15 13:47 ` [OE-core] " Stefano Babic
2021-03-15 14:46 ` Mike Looijmans
2021-03-15 14:58 ` Stefano Babic [this message]
2021-03-15 15:17 ` Mike Looijmans
[not found] ` <166C8D08E44901C2.email@example.com>
2021-03-18 13:48 ` Mike Looijmans
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