kernel-debugging-notes.txt

1. How do I symbolicate kernel panic traces?

Just add keepsyms=1 to either the Kernel Flags setting in /Library/Preferences/SystemConfiguration/com.apple.Boot.plist,
or to the boot-args NVRAM variable. Reboot, and any subsequent panics will be automatically symbolicated. You can run
mangled C++ symbols through the c++filt command line utility to get the proper C++ function signatures.

$ sudo nvram boot-args="-v keepsyms=1"

Thanks for Phil Dennis-Jordan for this great tip.

2. Debugging a AVX related crash which occurs at bootup.

$ nm /System/Library/Extensions/corecrypto.kext/Contents/MacOS/corecrypto | grep avx
0000000000001840 T _ccsha256_vng_intel_avx1_compress
0000000000036708 T _ccsha256_vng_intel_avx2_compress
0000000000026973 T _ccsha512_vng_intel_avx1_compress
00000000000327cb T _ccsha512_vng_intel_avx2_compress
000000000001d960 T _gcmDecrypt_avx1
000000000001c980 T _gcmEncrypt_avx1

$ gdb /System/Library/Extensions/corecrypto.kext/Contents/MacOS/corecrypto
(gdb) x/16i 0x0000000000001840
   0x1840:	push   %rbp
   0x1841:	mov    %rsp,%rbp
   0x1844:	push   %rbx
   0x1845:	push   %r12
   0x1847:	push   %r13
   0x1849:	push   %r14
   0x184b:	push   %r15
   0x184d:	sub    $0x168,%rsp
   0x1854:	lea    0x60(%rsp),%rax
   0x1859:	and    $0xffffffffffffffe0,%rax
   0x185d:	vmovdqa %ymm0,(%rax)  <--- the crash occurs here due to lack of "xsave" support