Hi Peter, to reproduce the difference, you just need a kernel with POSIX ACL enabled for your FS (e.g. CONFIG_FS_POSIX_ACL=y; CONFIG_EXT4_FS_POSIX_ACL=y). The problem is that 'cp -a' when copying a directory without any ACLs attached will for whatever reason try to assign an empty posix_acl_default list to the target directory. Linux kernel will always filter it out, but pseudo just creates empty list. Later in the build process, when bootable image is created, it will instantiate a directory with empty posix_acl_default list on the bootable media. When you will try to perform certain operations on such directory (e.g. creating another directory inside it), kernel, namely ext4_get_acl, if I resemble correctly, will return EINVAL error, so the resulting filesystem will be effectively broken in many ways.
There is an issue [1] in Automotive Grade Linux Jira with an example of erroneous behaviour. The tricky part of it is that the error itself can not be reproduced easily: although I have one kernel config of a machine that makes broken images, I couldn't repeat it on later kernel versions. But the setfattr/getfattr behaviour difference that causes that error can be reproduced quite easily on any kernel with ACLs enabled. [1] (Starting with Jan-Simon Moeller's comment on 26th of October) https://jira.automotivelinux.org/browse/SPEC-254?focusedCommentId=11313&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-11313 On 02/24/2017 04:05 PM, Seebs wrote: > On Fri, 24 Feb 2017 15:48:15 +0100 > an...@advancedtelematic.com wrote: > >> From: Anton Gerasimov <an...@advancedtelematic.com> >> >> The difference between what we see in pseudo and what happens without >> pseudo can be seen by typing: >> >> mkdir setfattr-test >> setfattr -n system.posix_acl_default -v 0x02000000 setfattr-test >> getfattr -n system.posix_acl_default setfattr-test >> >> Under some kernel configurations this difference leads to annoying >> errors, e.g. directories copied with 'cp -a' get broken in a fancy >> way. > Can you expand on this? What is happening to make the "erroneous" ACLs? > What kernel configurations? > > -s -- Anton Gerasimov, ATS Advanced Telematic Systems GmbH Kantstrasse 162, 10623 Berlin Managing Directors: Dirk Pöschl, Armin G. Schmidt Register Court: HRB 151501 B, Amtsgericht Charlottenburg -- _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto
