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

Eric Seidel eric at webkit.org
Fri Oct 7 12:09:56 PDT 2011

At least as of Snow Leopard, it was impossible to run the layout
tests, without a login-session/security context.

You would need to be physically logged into the machine, and then run
the tests from VNC/Remote Desktop for them to work.  In snow leopard
SSHing to a machine (without being physically logged in) did not
create the right kind of session to support DumpRenderTree (which
needs to talk to the pasteboard and window servers among other

It may be possible to run the tests from SSH if you are also logged
via the console.

It used to be the case that you could run a Mac headless, but you need
to boot them with a monitor attached if you wanted things like the
layout tests and performance tests (like the PLT) to run correctly.
(You could disconnect the monitor after initial boot and the mac would
behave as though it was connected.)


On Fri, Oct 7, 2011 at 1:53 PM, 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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