Hello Benjamin, some of the Ubuntu supported boards (e.g. LicheeRV) have so little RAM that a default initrd cannot be decompressed. Some boards may need modules that are not in initrd by default.
Best regards Heinrich Benjamin Drung <bdr...@ubuntu.com> schrieb am Sa., 8. Juli 2023, 02:19: > Hi all, > > a year ago we changed the default compression and level for the > initramfs to zstd -1. This fixed the very slow creation times on > development boards (see bug #1958148), but that leads to bigger > initramfs sizes that triggered other bugs (like bug #1842320). > Big initramfs sizes can also fill up small sized /boot partitions easily > (grooming the 850 initramfs-tools bugs revealed several such reports). > > Using xz -9 would give very good compression, but it takes very long > (especially on slow development boards) and a lot of memory (good luck > on Raspberry Pis with small memory like Pi Zeros). > > I propose following approach to address the drawback: Create cpio > archives (compressed with xz -9) for the kernel modules and firmware > files when building the kernel/firmware Debian package. Then ship those > cpio archives in the package (or in a separate binary package). Then the > CPU load it put on the builders. The cpio archives would contain the > modules for MODULES=most. > > mkinitramfs will then look for those cpio archives and uses those in > case they are present. Such a initramfs would look like this: > > * AMD/Intel microcode cpio archive (on amd64) > * main cpio archive compressed with zstd -1 > * kernel modules from the Debian package compressed with xz -9 > * firmware files from the Debian package compressed with xz -9 > > After working on initramfs-tools as part my day job, my fingers were > itching and I had to create a quick and dirty draft in my free night > time. You can find the result of the last two hours in [1]. This draft > has a mkinitramfs-kernel script that creates a cpio archive containing > the kernel modules and firmware (that needs to be split later on). > > The lunar test result on my AMD Ryzen 7 5700G look promising: Building > 6.2.0-24-generic-modules-most.cpio.xz takes around 90 seconds and is > 54.9 MiB in size. Creating the initramfs speeds up from around 8.7 > seconds to 3.5 seconds (saves 60 %). The size reduces from 133.1 MiB to > 80.7 MiB (saves 39.4 %). So the boot needs 52.4 MiB less, but > /lib/modules need 54.9 MiB for the cpio archive. > > The drawback is that building the kernel would take longer, the package > takes more space on the archive and mirrors, and downloading them could > take longer on slow connections. > > Implementing my proposal would be relative easy for initramfs-tools, but > would mean some work for the kernel team. > > What do you think? > > [1] > https://code.launchpad.net/~bdrung/ubuntu/+source/initramfs-tools/+git/initramfs-tools/+ref/ubuntu/prebuilt > > -- > Benjamin Drung > Debian & Ubuntu Developer > > -- > ubuntu-devel mailing list > ubuntu-devel@lists.ubuntu.com > Modify settings or unsubscribe at: > https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel >
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