nickdesaulniers added a comment. Hey! Looks like Diff 404763 for an x86 defconfig plus CONFIG_ZERO_CALL_USED_REGS=y starts booting! Looks like it panics though trying to launch `init`(pid 1) though.
[ 0.702163] Run /bin/sh as init process [ 0.702913] Failed to execute /bin/sh (error -22) [ 0.703721] Run /sbin/init as init process [ 0.704454] Starting init: /sbin/init exists but couldn't execute it (error -22) [ 0.705702] Run /etc/init as init process [ 0.706390] Run /bin/init as init process [ 0.707037] Run /bin/sh as init process [ 0.707736] Starting init: /bin/sh exists but couldn't execute it (error -22) [ 0.708895] Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance. [ 0.711246] CPU: 1 PID: 1 Comm: sh Not tainted 5.16.0-12116-g74e25defe135 #6 [ 0.712426] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 [ 0.713778] Call Trace: [ 0.714188] <TASK> [ 0.714578] dump_stack_lvl+0x65/0x9a [ 0.715190] panic+0x101/0x295 [ 0.715743] ? _printk+0x54/0x80 [ 0.716297] ? rest_init+0xd0/0xd0 [ 0.716882] kernel_init+0x18b/0x190 [ 0.717525] ret_from_fork+0x22/0x30 [ 0.718138] </TASK> [ 0.721159] Kernel Offset: 0xe800000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 0.722977] ---[ end Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance. ]--- If I disable `CONFIG_ZERO_CALL_USED_REGS=y`, I can launch userspace just fine. (`Error -22` corresponds to `EINVAL` FWIW). Perhaps some kernel code related to launching init (or processes, generally) isn't happy with a zero'd register somewhere, or we have another codegen bug. Either way, that needs to be investigated+fixed before merging. Probably could sprinkle `subdir-ccflags-y += -fzero_call_used_regs=skip` (or whatever) in various Makefiles to pinpoint which object file is affected, then take a look at the disassembly from there. (or add function attributes to get more fine grained). It looks like the Kconfig detection for `CONFIG_CC_HAS_ZERO_CALL_USED_REGS` is working correctly now. i.e. $ ARCH=arm64 make LLVM=1 -j72 defconfig $ grep -rn ZERO_CALL_USED_REGS .config $ make LLVM=1 -j72 defconfig $ grep -rn ZERO_CALL_USED_REGS .config 4230:CONFIG_CC_HAS_ZERO_CALL_USED_REGS=y 4231:# CONFIG_ZERO_CALL_USED_REGS is not set (LGTM) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D110869/new/ https://reviews.llvm.org/D110869 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
