Messages in this thread | | | Date | Fri, 3 Jul 2015 17:23:03 +0200 | From | Jan Kara <> | Subject | Non-booting current Linus' tree |
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Hello,
so I was wondering why I cannot boot current Linus' tree in my kvm instance. The boot dies after writing "Booting the kernel" message. After some bisection I have identified the culprit is in commit 91a8c2a5b43fc4be4adb4bda50cd331697e289e0 (x86/fpu: Clean up and fix MXCSR handling). After applying that commit I start to get oopses like:
general protection fault: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.1.0-rc4-xen+ #18 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: ffffffff8180d4c0 ti: ffffffff81800000 task.ti: ffffffff81800000 RIP: 0010:[<ffffffff81048a6c>] [<ffffffff81048a6c>] mxcsr_feature_mask_init+0x1c/0x40 RSP: 0000:ffffffff81803ba8 EFLAGS: 00010082 RAX: 0000000000000000 RBX: 00000000ffff8800 RCX: 0000000000000000 RDX: 0020400000000000 RSI: 0000000000000000 RDI: ffffffff81803da8 RBP: ffffffff81803da8 R08: 7f0089011d402087 R09: 00000000ffff8800 R10: 7f0089011d402087 R11: 00000000ffff8800 R12: ffff88007f004000 R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000008 FS: 0000000000000000(0000) GS:ffff88007f000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88000269a000 CR3: 0000000001808000 CR4: 00000000000006b0 Stack: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<ffffffff81048beb>] fpu__init_system+0x2b/0x190 [<ffffffff81048d5e>] fpu__cpu_init+0xe/0x10 [<ffffffff8104eac3>] cpu_init+0x3a3/0x430 [<ffffffff810794b1>] ? fill_pte+0x31/0x140 [<ffffffff8107975d>] ? set_pte_vaddr_pud+0x4d/0x60 [<ffffffff814058c0>] ? do_softirq_own_stack+0x30/0x30 [<ffffffff81881519>] trap_init+0x4bb/0x602 [<ffffffff8189d583>] ? inode_init_early+0x5a/0x98 [<ffffffff8187efea>] start_kernel+0x265/0x4e1 [<ffffffff8187eb7d>] ? set_init_arg+0x6a/0x6a [<ffffffff8187e565>] x86_64_start_reservations+0x1b/0x32 [<ffffffff8187e6c3>] x86_64_start_kernel+0x147/0x156 [<ffffffff8187e120>] ? early_idt_handlers+0x120/0x120 Code: 05 00 c9 c3 66 2e 0f 1f 84 00 00 00 00 00 90 55 31 c0 b9 40 00 00 00 48 89 e5 48 81 ec 00 02 00 00 48 8d bd 00 fe ff ff f3 48 ab <0f> ae 85 00 fe ff ff 8b 85 1c fe ff ff ba bf ff 00 00 85 c0 0f RIP [<ffffffff81048a6c>] mxcsr_feature_mask_init+0x1c/0x40 RSP <ffffffff81803ba8>
And indeed the oops happens at: 2b:* 0f ae 85 00 fe ff ff fxsave -0x200(%rbp) <-- trapping instruction
Because the address isn't 32-byte aligned (which I assume is the requirement from looking into the code). So clearly my gcc messed up and miscompiled the thing by ignoring the alignment attribute. Now my build host is rather old installation (SLES 11 SP3) running gcc 4.3.4 but there are quite a few installations of it still running. So do we care or should I just upgrade the build host?
Honza -- Jan Kara <jack@suse.cz> SUSE Labs, CR
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