Hi, On Fri, Dec 20, 2024 at 03:52:23AM -0800, Anton Antonov via lists.yoctoproject.org wrote: > On Fri, Dec 20, 2024 at 12:02 AM, Mikko Rapeli wrote: > > PMEM enables firmware to provide large memory block devices > > to the kernel. The firmware can download e.g. installer > > rootfs images to memory which kernel can then boot into.u-boot support has > > been added in > > https://lore.kernel.org/u-boot/20241203163605.1482152-2-sughosh.g...@linaro.org/ > > > > I don't think this feature should be genericarm64 specific. I think it should > be defined similar to x86 one: > https://git.yoctoproject.org/yocto-kernel-cache/tree/features/intel-persistent-memory/intel-x86-64-pmem.cfg > > and added to genericarm64 machine (and any other arm64 machine when required) > via MACHINE_FEATURES in the machine definition: > https://github.com/yoctoproject/poky/blob/master/meta-yocto-bsp/conf/machine/genericarm64.conf#L11
Ok, sounds sensible. Can someone help me how to apply changes to kernel-meta git tree via patches in SRC_URI? This way I can test the real thing and enable this via MACHINE_FEATURES. > > Build into kernel instead of modules since the driver is likely > > needed to find main rootfs, possibly inside initrd. > > genericarm64 machine includes initrd into images. But, the Yocto init script > doesn't load these drivers even if they are included into initrd and > DeviceTree includes a pmem node. I did a quick check but couldn't find an > obvious issue in the init script. I don't know what would be the best option > - either built-in the drivers or fix the init script and include the drivers > as modules. I prefer the latter (and it works with other Linux distros), but > I don't know how ease it would be to fix the init script. Yes, the initrd images are a bit arcane at the moment. I'd like to see an initrd with systemd, udev and a lot of kernel driver modules, which would get loaded if HW is detected. systemd services know to wait for udev if for example kernel driver for rootfs isn't immediately available. I'm trying to draft one for security and TPM related use cases. Cheers, -Mikko
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