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David Bakin (Exchange)
davidbak@Exchange.Microsoft.com
Thu, 24 Jun 1999 09:17:11 -0700
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Jonathon,
I have a question about how device state is restarted/recovered after a
crash and checkpoint recovery.
In the ongoing thread "some very thought provoking questions" you
distinguish between the kernel, which is rebooted/restarted, and the
processes running, which are checkpointed and continued. And you also
mentioned how 'external connections' are revoked, and a process can then get
a notification and perform some recovery (like revalidate a capability).
So is it the case that on reboot the device drivers - presumably part of the
kernel - reinitialize all external hardware to some known state? And then
processes which talk to hardware, on discovering that their capability is
now invalid, know that they need to recover which may including setting the
hardware to other states? I guess part of the question may be are "device
drivers" entirely kernel mode, or do they tend to be written as a kernel
mode part and a process part, or what? In practice what kinds of device
state are kept in the kernel and which in processes (checkpointed, and then
verified?)
Thanks! -- Dave
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<DIV><FONT face=Verdana size=2><SPAN
class=230301316-24061999>Jonathon,</SPAN></FONT></DIV>
<DIV><FONT face=Verdana size=2><SPAN
class=230301316-24061999></SPAN></FONT> </DIV>
<DIV><FONT face=Verdana size=2><SPAN class=230301316-24061999>I have a question
about how device state is restarted/recovered after a crash and checkpoint
recovery. </SPAN></FONT></DIV>
<DIV><FONT face=Verdana size=2><SPAN
class=230301316-24061999></SPAN></FONT> </DIV>
<DIV><FONT face=Verdana size=2><SPAN class=230301316-24061999>In the ongoing
thread "some very thought provoking questions" you distinguish between the
kernel, which is rebooted/restarted, and the processes running, which are
checkpointed and continued. And you also mentioned how 'external
connections' are revoked, and a process can then get a notification and perform
some recovery (like revalidate a capability).</SPAN></FONT></DIV>
<DIV><FONT face=Verdana size=2><SPAN
class=230301316-24061999></SPAN></FONT> </DIV>
<DIV><FONT face=Verdana size=2><SPAN class=230301316-24061999>So is it the case
that on reboot the device drivers - presumably part of the kernel - reinitialize
all external hardware to some known state? And then processes which talk
to hardware, on discovering that their capability is now invalid, know that they
need to recover which may including setting the hardware to other states?
I guess part of the question may be are "device drivers" entirely kernel mode,
or do they tend to be written as a kernel mode part and a process part, or
what? In practice what kinds of device state are kept in the kernel and
which in processes (checkpointed, and then verified?)</SPAN></FONT></DIV>
<DIV><FONT face=Verdana size=2><SPAN
class=230301316-24061999></SPAN></FONT> </DIV>
<DIV><FONT face=Verdana size=2><SPAN class=230301316-24061999>Thanks! --
Dave</SPAN></FONT></DIV></BODY></HTML>
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