Kdrive KdCardInfo.selected rationale

Andrew Christian andrewdchristian at gmail.com
Fri Jul 27 20:35:27 PDT 2007

I spent a little time today hacking Ephyr to support multiple desktop
screens and ran into a confusing variable in the KdCardInfo data

Each screen is attached to a card data structure which has a
"selected" field.  When the screen is enabled (KdEnableScreen) the
selected field is set to the number of the screen.  The KdInitScreen
function checks to see if the selected field matches the screen
number, and if so, it enables the screen.  Unfortunately, the default
startup order of Kdrive calls KdInitScreen initially once for each
screen and then calls KdEnableScreen just once for the first screen.
The result is one enabled and N disabled screens.

Everything appears to work fine if I comment out the "selected"
checks, but I'm left with the nagging suspicion that I am
misunderstanding the design.  Can anyone explain the purpose of the
selected field?


 - Andrew

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