On 12/08/2020 8:51 pm, Baesken, Matthias wrote:
Hi Yasumasa , I'm more or less fine with the change .
But still not fully convinced that removing the iteration is a good thing .
http://cr.openjdk.java.net/~ysuenaga/JDK-8250598/webrev.01/src/hotspot/cpu/x86/vm_version_x86.cpp.frames.html
1827 for (base = 0x40000000; base < 0x40010000; base += 0x100) {
1828 check_virt_cpuid(base, registers);
I think just checking "0x40000000" should work in most cases but if I remember
correctly sometimes it was not enough .
See also some references about Xen/KVM :
https://lists.linuxfoundation.org/pipermail/virtualization/2012-May/019974.html
"If compat mode for another h/v is enabled then those leaves will appear
at 0x40000000 and Xen's will be bumped up, so a fully Xen aware set of
drivers (or detection routine, etc) should check at 0x100 intervals
until 0x40010000 "
and
https://lore.kernel.org/patchwork/patch/394371/
And not so happy about the WMI usage (called in early JVM startup) :
http://cr.openjdk.java.net/~ysuenaga/JDK-8250598/webrev.01/src/hotspot/os_cpu/windows_x86/vm_version_windows_x86.cpp.frames.html
bool VM_Version::is_in_VM() { ... }
...
}
But if noone else complains about it, I guess it's okay .
I haven't reviewed this because I don't understand any of the code. But
all that extra stuff during VM initialization doesn't look good to me.
We do not want to pay a startup penalty just because we want a more
accurate hypervisor listing in an error report!
Can we not determine this only if needed? (Granted doing all this stuff
during crash reporting may also be an issue.)
David
-----
Best regards, Matthias
PING: Could you review this change?
JBS: https://bugs.openjdk.java.net/browse/JDK-8250598
webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8250598/webrev.01/
Build change has been reviewed by Erik.
