2012-08-18

dynamic linking to video driver

7.11: bk.addm/Gordon Letwin`Inside OS#2:
[8.13: intro:
os/2 was microsoft's next big thing for 1998,
but it never happened despite being
a leap forward in security .
. in this reading session,
I was wondering how it dealt with the issue of
unstable drivers . intro's dynamic linking .]
p89: the familiar static linking:
. the linker handles static links by
noting which symbols are marked external
and hooking those up with similar symbols
to be found in accompanying .obj files .
p29: the new dynamic linking:
. dynamic linking is how operating systems can be
extended or patched by the user or the apps;
just like hardware can accept new circuit boards .
p13:
. because drivers needed protected mode
there would need to be a mode transition
with every write to the display
but we avoid this by having apps
not access device drivers directly;
rather they do so through dynamic linking .
[. how does that explain it?
is dyna'linking facilitating our ability to
run device drivers in user mode?]
p109:
. dyna'linking to the video display driver
is possible because it doesn't require
hardware interrupts;
drivers are generally located in the kernel
only because some are needing access to
hardware interrupts .