* describe crashs in UEFI binaries * provide architechture specific information for the sandbox and RISC-V

Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com --- v2: describe CONFIG_ARMV8_SPL_EXCEPTION_VECTORS --- doc/develop/crash_dumps.rst | 60 +++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+)

diff --git a/doc/develop/crash_dumps.rst b/doc/develop/crash_dumps.rst index 85030b4e36..b7b81bdce5 100644 --- a/doc/develop/crash_dumps.rst +++ b/doc/develop/crash_dumps.rst @@ -122,3 +122,63 @@ If we want to dive deeper, we can disassemble the U-Boot binary::

This example is based on the ARMv8 architecture but the same procedures can be used on other architectures as well. + +Crashs in UEFI binaries +----------------------- + +If UEFI images are loaded when a crash occurs, their load addresses are +displayed. If the process counter points to an address in a loaded UEFI +binary, the relative process counter position is indicated. Here is an +example executed on the U-Boot sandbox:: + + => load host 0:1 $kernel_addr_r buggy.efi + 5632 bytes read in 0 ms + => bootefi $kernel_addr_r + Booting /buggy.efi + Buggy world! + + Segmentation violation + pc = 0x19fc264c, pc_reloc = 0xffffaa4688b1664c + + UEFI image [0x0000000019fc0000:0x0000000019fc6137] pc=0x264c '/buggy.efi' + +The crash occured in UEFI binary buggy.efi at relative position 0x264c. +Disassembly may be used to find the actual source code location:: + + $ x86_64-linux-gnu-objdump -S -D buggy_efi.so + + 0000000000002640 <memset>: + 2640: f3 0f 1e fa endbr64 + 2644: 48 89 f8 mov %rdi,%rax + 2647: 48 89 f9 mov %rdi,%rcx + 264a: eb 0b jmp 2657 <memset+0x17> + 264c: 40 88 31 mov %sil,(%rcx) + +Architecture specific details +----------------------------- + +ARMv8 +~~~~~ + +On the ARM 64-bit architecture CONFIG_ARMV8_SPL_EXCEPTION_VECTORS controls +if the exception vector tables are set up in the Secondary Program Loader (SPL). +Without initialization of the tables crash dumps cannot be shown. The feature is +disabled by default on most boards to reduce the size of the SPL. + +RISC-V +~~~~~~ + +On the RISC-V architecture CONFIG_SHOW_REGS=y has to be specified to show +all registers in crash dumps. + +Sandbox +~~~~~~~ + +The sandbox U-Boot binary must be invoked with parameter *-S* to display crash +dumps: + +.. code-block:: bash + + ./u-boot -S -T + +Only with CONFIG_SANDBOX_CRASH_RESET=y the sandbox reboots after a crash.