x86 stack check fail w/posix-lib & newlib

[galak]

When trying to run the posix tests w/newlib as enabled by PR #13685

./scripts/sanitycheck -T tests/posix/ -p qemu_x86

qemu_x86 tests/posix/common/portability.posix.newlib FAILED: handler_crash

We get:

SDK 0.9.5:

SeaBIOS (version rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org)
Booting from ROM..***** Booting Zephyr OS v1.14.0-rc1-501-ge03b7fad46 *****
***** Double Fault *****
***** Stack Check Fail! *****
Current thread ID = 0x00403160
eax: 0x00000001, ebx: 0x004011e0, ecx: 0x00000000, edx: 0x0043e00c
esi: 0x00401020, edi: 0x00400000, ebp: 0x004011e0, esp: 0x0043e000
eflags: 0x00000202 cs: 0x0008
call trace:
eip: 0x00002cc7
     corrupted? (bp=0x004011e0)
Fatal fault in essential thread! Spinning...
Terminate emulator due to fatal kernel error

SDK 0.10.0:

SeaBIOS (version rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org)
Booting from ROM..***** Booting Zephyr OS v1.14.0-rc1-501-ge03b7fad46 *****
***** Double Fault *****
***** Stack Check Fail! *****
Current thread ID = 0x00403160
eax: 0x00000001, ebx: 0x0043e064, ecx: 0x00000000, edx: 0x00000012
esi: 0x004011dc, edi: 0x0043e060, ebp: 0x0043e040, esp: 0x0043dfd8
eflags: 0x00000202 cs: 0x0008
call trace:
eip: 0x000026f3
     0x0000275e (0x401020)
     0x00001e26 (0x401020)
     0x000016ed (0x401020)
     0x00001568 (0x401020)
     0x0000a616 (0x14c4f)
     0x00003255 (0x124bd)
     0x0000a7f0 (0x4430ec)
     0x0000ac27 (0x43e1e4)
Fatal fault in essential thread! Spinning...
Terminate emulator due to fatal kernel error

[nashif]

@galak why was this merged although it is known to be failing? Now all CI jobs are failing because of this.

[galak]

@galak why was this merged although it is known to be failing? Now all CI jobs are failing because of this.

My bad, wasn't thinking about the CI impact to everything else.

Is there someone who can look at the x86 issue.

[andrewboie]

The error message is correct; this is a stack overflow in _main_thread.
It appears if CONFIG_ZTEST is enabled, CONFIG_MAIN_STACK_SIZE defaults to 512, which is not enough.

[andrewboie]

@galak I've unpeeled this enough to see what is going on.

For this test, CONFIG_STDOUT_CONSOLE=y, which causes TC_PRINT() and related macros to map to libc printf() instead of the kernel's printk(). Newlib's printf() uses tons of stack space, even more than minimal libc, and LOTS more than printk(), and we are blowing stack in _ztest_run_test_suite() before the test can even run.

For some reason, CONFIG_STDOUT_CONSOLE is defaulting to Y when newlib is enabled:

config STDOUT_CONSOLE
	bool "Send stdout to console"
	depends on CONSOLE_HAS_DRIVER
	default NEWLIB_LIBC
	help
	  This option directs standard output (e.g. printf) to the console
	  device, rather than suppressing it entirely. See also EARLY_CONSOLE
	  option.

I think the right thing to do is always enable CONFIG_STDOUT_CONSOLE, but get rid of this policy which is redirecting testcase output to printf just because it is turned on.