On Fri, 2025-03-21 at 13:27 +0800, Gao Xiang wrote: > Hi Christoph, > > On 2025/3/21 13:01, Christoph Hellwig wrote: > > We've been trying to kill off initrd in favor of initramfs for about > > two decades. I don't think adding new file system support to it is > > helpful. > > > > Disclaimer: I don't know the background of this effort so > more background might be helpful. So erofs came up in an effort to improve the experience for users of NixOS on smaller systems. We use erofs a lot and some people in the community just consider it a "better" cpio at this point. A great property is that the contents stays compressed in memory and there is no need to unpack anything at boot. Others like that the rootfs is read-only by default. In short: erofs is a great fit. Of course there are some solutions to using erofs images at boot now: https://github.com/containers/initoverlayfs But this adds yet another step in the already complex boot process and feels like a hack. It would be nice to just use erofs images as initrd. The other building block to this is automatically sizing /dev/ram0: https://lkml.org/lkml/2025/3/20/1296 I didn't pack both patches into one series, because I thought enabling erofs itself would be less controversial and is already useful on its own. The autosizing of /dev/ram is probably more involved than my RFC patch. I'm hoping for some input on how to do it right. :) > > Two years ago, I once thought if using EROFS + FSDAX to directly > use the initrd image from bootloaders to avoid the original initrd > double caching issue (which is what initramfs was proposed to > resolve) and initramfs unnecessary tmpfs unpack overhead: > https://lore.kernel.org/r/ZXgNQ85PdUKrQU1j@xxxxxxxxxxxxx > > Also EROFS supports xattrs so the following potential work (which > the cpio format doesn't support) is no longer needed although I > don't have any interest to follow either): > https://lore.kernel.org/r/20190523121803.21638-1-roberto.sassu@xxxxxxxxxx Thanks for the pointers! Julian
