Hi Frank, On Mon, 23 Aug 2021 05:01:15 +0100, Frank Rowand <frowand.list@xxxxxxxxx> wrote: > > Hi Marc, > > On 8/20/21 9:47 AM, Marc Zyngier wrote: > > Trying to boot without SYSFS, but with OF_DYNAMIC quickly > > results in a crash: > > > > [ 0.088460] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070 > > [...] > > [ 0.103927] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.14.0-rc3 #4179 > > [ 0.105810] Hardware name: linux,dummy-virt (DT) > > [ 0.107147] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--) > > [ 0.108876] pc : kernfs_find_and_get_ns+0x3c/0x7c > > [ 0.110244] lr : kernfs_find_and_get_ns+0x3c/0x7c > > [...] > > [ 0.134087] Call trace: > > [ 0.134800] kernfs_find_and_get_ns+0x3c/0x7c > > [ 0.136054] safe_name+0x4c/0xd0 > > [ 0.136994] __of_attach_node_sysfs+0xf8/0x124 > > [ 0.138287] of_core_init+0x90/0xfc > > [ 0.139296] driver_init+0x30/0x4c > > [ 0.140283] kernel_init_freeable+0x160/0x1b8 > > [ 0.141543] kernel_init+0x30/0x140 > > [ 0.142561] ret_from_fork+0x10/0x18 > > > > While not having sysfs isn't a very common option these days, > > it is still expected that such configuration would work. > > > > Paper over it by bailing out from __of_attach_node_sysfs() if > > CONFIG_SYSFS isn't enabled. > > CONFIG_SYSFS should be automatically selected when CONFIG_OF_DYNAMIC > is enabled, and it should not be possible to disable CONFIG_SYSFS > in this case. OF_DYNAMIC selects OF_KOBJ, which itself doesn't actually depends on SYSFS. It merely has a "def_bool SYSFS". If a stronger dependency is expected, that's probably where it should be expressed. However, kobj.c already has a couple of if (!IS_ENABLED(CONFIG_SYSFS)) return 0; sprinkled over it, so there is already an assumption that it can be build without SYSFS. > > Can you send your .config? https://pastebin.com/MmRWuxLr > What ARCH did you build the kernel with? That's an arm64 build. Thanks, M. -- Without deviation from the norm, progress is not possible.
