Messages in this thread |  | | Date | Sat, 28 Apr 2018 11:18:23 +0200 | From | Ingo Molnar <> | Subject | Re: [RFD] x86: The future of MPX |
| |
* Thomas Gleixner <tglx@linutronix.de> wrote:
> Dave, > > I've got the following MPX related information: > > .... But they [Intel] certainly haven't maintained the whole MPX support > in GCC at all since two or three years (e.g. bootstrap with MPX was broken > since forever), so now it's gone from GCC. .... > > and I know that GCC is discussing MPX removal since May last year at least. > To the best of my knowledge clang does not support it either. > > So what's the state of this stuff? If we don't have a compiler supporting > it how on earth is that useful or even testable for anyone who does not > have access to some magic Intel internal compiler version? > > If that's the sad state of affairs, then we just should move the whole > stuff into staging or simply queue it for removal in 4.18.
I just tried the MPX testcases with the latest kernel:
deimos:~/tip/tools/testing/selftests/x86> ./mpx-mini-test_64 XSAVE is supported by HW & OS XSAVE processor supported state mask: 0x21f XSAVE OS supported state mask: 0x21f BNDREGS: size: 64 user: 1 supervisor: 0 aligned: 0 BNDCSR: size: 64 user: 1 supervisor: 0 aligned: 0 mpx-mini-test_64: mpx-mini-test.c:58: write_int_to: Assertion `fd >= 0' failed. Aborted (core dumped)
deimos:~/tip/tools/testing/selftests/x86> ./mpx-mini-test_32 XSAVE is supported by HW & OS XSAVE processor supported state mask: 0x21f XSAVE OS supported state mask: 0x21f BNDREGS: size: 64 user: 1 supervisor: 0 aligned: 0 BNDCSR: size: 64 user: 1 supervisor: 0 aligned: 0 mpx-mini-test_32: mpx-mini-test.c:58: write_int_to: Assertion `fd >= 0' failed. Aborted (core dumped)
... and both of them crashed.
The CPU has MPX support and the kernel has CONFIG_X86_INTEL_MPX=y:
deimos:~> dmesg | grep -i mpx [ 0.000000] x86/fpu: Supporting XSAVE feature 0x008: 'MPX bounds registers' [ 0.000000] x86/fpu: Supporting XSAVE feature 0x010: 'MPX CSR'
Thanks,
Ingo
|  |