- I had errantly assumed that all user requests should run with interrupts
enabled. User requests for software interrupts, however, need to disable
interrupts (and tracing) just like hardware interrupts.
- Disable alignment checking when emulating a hardware interrupt as well
(based on the description of the real mode operation of the 'INT'
instruction in the IA-32 manuals).
- Use constants for fields in %eflags.
Tested by: bz
MFC after: 3 days
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