On 16 November 2013 17:49, Eitan Adler <li...@eitanadler.com> wrote:
> On Sat, Nov 16, 2013 at 4:12 PM, Zach Crum <crum.z...@gmail.com> wrote:
>> This setting is not listed in /boot/defaults/loader.conf. Is it supposed to
>> be singular or plural?
> I will commit the patch.
The FAQ update patch looks fine.
> Does any know of cases where this memory test actually catches errors?
> How important is it?
The boot time test is primarily of historical significance, and
doesn't really provide value on contemporary systems. It's mainly a
workaround for ancient broken BIOSes that might return bogus memory
map data. I intend to commit the patch below that disables it by
The variable name is "hw.memtest.tests" as it's intended to be
extended to a bitmap of tests to run at boot, with other bits
representing more comprehensive tests.
Author: Ed Maste <ema...@freebsd.org>
Date: Thu Nov 21 12:31:06 2013 -0500
Disable amd64 boot time memory test by default
The page presence memory test takes a long time on large memory systems
and has little value on contemporary amd64 hardware.
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index 7f05d58..df03e55 100644
@@ -1476,13 +1476,15 @@ getmemsize(caddr_t kmdp, u_int64_t first)
Maxmem = atop(physmem_tunable);
- * By default enable the memory test on real hardware, and disable
- * it if we appear to be running in a VM. This avoids touching all
- * pages unnecessarily, which doesn't matter on real hardware but is
- * bad for shared VM hosts. Use a general name so that
- * one could eventually do more with the code than just disable it.
+ * The boot memory test is disabled by default, as it takes a
+ * significant amount of time on large-memory systems, and is
+ * unfriendly to virtual machines as it unnecessarily touches all
+ * pages.
+ * A general name is used as the code may be extended to support
+ * additional tests beyond the current "page present" test.
- memtest = (vm_guest > VM_GUEST_NO) ? 0 : 1;
+ memtest = 0;
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