[webkit-dev] layout tests cannot set Generic RGB Color Profile on headless MacPro?

Elliot Poger epoger at google.com
Fri Oct 7 13:05:08 PDT 2011

On Fri, Oct 7, 2011 at 3:06 PM, Ryosuke Niwa <rniwa at webkit.org> wrote:

> Yeah, layout tests fail on Mac without a screen connected to it. Chromium
> buildbots use Mac minis connected to KVMs for that reason. I'm actually
> surprised to learn that tests passed on a headless Mac mini.

Ah, then you will perhaps NOT be surprised to learn: that MacMini actually
WAS plugged into a monitor (but the monitor was far away and hadn't been
turned on for months--thus I forgot about it).

I plugged a monitor into the MacPro, and unplugged the monitor from the
MacMini, and established the following for both MacPro and MacMini
(restarting the computer each time):

- monitor plugged in and turned on: layout tests work fine
- monitor plugged in and turned off: layout tests work fine
- no monitor plugged in: layout tests break

I also tried plugging various adapters (Mini DisplayPort to DVI, Mini
DisplayPort to VGA, HDMI to DVI) into the computer but *not* connecting a
monitor to them; in all cases, it was the same as plugging in no monitor
cable at all (layout tests break).

Presumably connecting to a KVM or other "fake monitor", as Ryosuke mentions,
would work.

Thanks all for the information.

> - Ryosuke
> On Fri, Oct 7, 2011 at 11:53 AM, Simon Fraser <simon.fraser at apple.com>wrote:
>> On Oct 7, 2011, at 11:45 AM, Elliot Poger wrote:
>> > I was having problems with lots of image mismatches running WebKit
>> layout tests on a headless MacPro (10.6.8).  (The image diffs were very
>> minor adjustments in scroll bar shading.)
>> >
>> > Eventually, out of frustration, I tried running the same test on that
>> headless MacPro as well as my desktop MacPro (also 10.6.8).  The test
>> succeeded on my desktop MacPro but not the headless MacPro.
>> >
>> > One difference I have noticed is that the Display Profile (under System
>> Preferences > Displays > Color) is set to "sRGB IEC61966-2.1" (my desktop
>> was set to "Generic RGB Profile").  I tried setting it to "Generic RGB
>> Profile" on the headless machine, but when I closed and reopened System
>> Preferences it had reverted to "sRGB IEC61966-2.1".
>> >
>> > I tried setting the Display Profile on my desktop to "sRGB
>> IEC61966-2.1", and the color scheme was noticeably brighter... but when I
>> ran layout tests afterwards, I saw that layout tests automatically set the
>> profile back to "Generic RGB Profile" temporarily for the test.  When I run
>> layout tests on the headless MacPro, it seems that it fails to change the
>> color profile (and I don't see any error in the output of layout tests).
>> >
>> > I tried it on a headless Mac Mini (10.6.8) and there layout tests was
>> able to change to Generic RGB Profile (and thus the tests passed).
>> >
>> > For now, my fix is going to be: don't run layout tests on headless
>> MacPros; use headless MacMinis instead.  Is this a Known Issue?  Any
>> suggestions?
>> I'm aware that there are color profile issues when running pixel tests,
>> but I was not aware of differences between hardware.
>> We may be able to fix DumpRenderTree/WebKitTestRunner to change the color
>> profile just for the test window, and not globally. I haven't tried that
>> yet.
>> Finally, I've noticed some changes in color profile behavior on Lion, so
>> if you try running tests there, you may see a new set of problems.
>> Simon
>> _______________________________________________
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>> webkit-dev at lists.webkit.org
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