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[TRUSTY,SRU,CONFIG] Disable CONFIG_CONTEXT_TRACKING_FORCE (LP: #1349028)

Message ID 1406795920-31452-1-git-send-email-colin.king@canonical.com
State New
Headers show

Commit Message

Colin Ian King July 31, 2014, 8:38 a.m. UTC 
From: Colin Ian King <colin.king@canonical.com>

SRU Justification:

Impact:

The CONFIG_CONTEXT_TRACKING_FORCE should be disabled for
various reasons:

1. As described in the Kconfig "this option brings an
overhead that you don't want in production" and also
"Say Y only if you're working on the development of an
architecture backend for the context tracking."

Clearly for production kernel we should disable this.

2. Disabling this option also fixes bug LP:#1349028.

Testcase:

According to the getitimer() man page: "The element
it_value is set to the amount of time remaining on
the timer, or zero if the timer is disabled. Similarly,
it_interval is set to the reset value."

The following perl script should never exit:

    use Time::HiRes;
    $SIG{VTALRM} = sub { };
    Time::HiRes::setitimer(&Time::HiRes::ITIMER_VIRTUAL, 0.5, 0.4);
    while (1) {
        my @t = Time::HiRes::getitimer(&Time::HiRes::ITIMER_VIRTUAL);
        exit 0 if $t[0] == 0;
    }

With this config change the correct behaviour occurs.

Note: I've not yet resolved why CONFIG_CONTEXT_TRACKING_FORCE
enabled causes the bug in the getitimer behaviour, for now disabling
this option is adequate; I'll look at that one I get back from
my vacation in a few weeks time.

Also, I may be on vaction when the SRU testing is required.
Perhaps somebody can step in and pick this up if required. Thanks.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 debian.master/config/config.common.ubuntu |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Tim Gardner July 31, 2014, 12:30 p.m. UTC | #1 
The help text for this option is gibberish. It is also surprising that 
armhf wants to default to Y.
diff mbox

Patch

diff --git a/debian.master/config/config.common.ubuntu b/debian.master/config/config.common.ubuntu
index 0e497ef..185b8cf 100644
--- a/debian.master/config/config.common.ubuntu
+++ b/debian.master/config/config.common.ubuntu
@@ -1196,7 +1196,7 @@  CONFIG_CONSOLE_POLL=y
 CONFIG_CONSOLE_TRANSLATIONS=y
 CONFIG_CONTEXT_SWITCH_TRACER=y
 CONFIG_CONTEXT_TRACKING=y
-CONFIG_CONTEXT_TRACKING_FORCE=y
+# CONFIG_CONTEXT_TRACKING_FORCE is not set
 CONFIG_COPS=m
 CONFIG_COPS_DAYNA=y
 CONFIG_COPS_TANGENT=y