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><H1
><A
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></A
>Glossary</H1
><DL
><DT
><A
NAME="GLOSS-BH"
></A
><B
>bh</B
></DT
><DD
><P
> Bottom Half: for historical reasons, functions with
`_bh' in them often now refer to any software interrupt, e.g.
<TT
CLASS="FUNCTION"
>spin_lock_bh()</TT
> blocks any software interrupt
on the current CPU. Bottom halves are deprecated, and will
eventually be replaced by tasklets. Only one bottom half will be
running at any time.
</P
></DD
><DT
><A
NAME="GLOSS-HWINTERRUPT"
></A
><B
>Hardware Interrupt / Hardware IRQ</B
></DT
><DD
><P
> Hardware interrupt request. <TT
CLASS="FUNCTION"
>in_irq()</TT
> returns
<SPAN
CLASS="RETURNVALUE"
>true</SPAN
> in a hardware interrupt handler (it
also returns true when interrupts are blocked).
</P
></DD
><DT
><A
NAME="GLOSS-INTERRUPTCONTEXT"
></A
><B
>Interrupt Context</B
></DT
><DD
><P
> Not user context: processing a hardware irq or software irq.
Indicated by the <TT
CLASS="FUNCTION"
>in_interrupt()</TT
> macro
returning <SPAN
CLASS="RETURNVALUE"
>true</SPAN
> (although it also
returns true when interrupts or BHs are blocked).
</P
></DD
><DT
><A
NAME="GLOSS-SMP"
></A
><B
><SPAN
CLASS="ACRONYM"
>SMP</SPAN
></B
></DT
><DD
><P
> Symmetric Multi-Processor: kernels compiled for multiple-CPU
machines. (CONFIG_SMP=y).
</P
></DD
><DT
><A
NAME="GLOSS-SOFTIRQ"
></A
><B
>softirq</B
></DT
><DD
><P
> Strictly speaking, one of up to 32 enumerated software
interrupts which can run on multiple CPUs at once.
Sometimes used to refer to tasklets and bottom halves as
well (ie. all software interrupts).
</P
></DD
><DT
><A
NAME="GLOSS-SWINTERRUPT"
></A
><B
>Software Interrupt / Software IRQ</B
></DT
><DD
><P
> Software interrupt handler. <TT
CLASS="FUNCTION"
>in_irq()</TT
> returns
<SPAN
CLASS="RETURNVALUE"
>false</SPAN
>; <TT
CLASS="FUNCTION"
>in_softirq()</TT
>
returns <SPAN
CLASS="RETURNVALUE"
>true</SPAN
>. Tasklets, softirqs and
bottom halves all fall into the category of `software interrupts'.
</P
></DD
><DT
><A
NAME="GLOSS-TASKLET"
></A
><B
>tasklet</B
></DT
><DD
><P
> A dynamically-registrable software interrupt,
which is guaranteed to only run on one CPU at a time.
</P
></DD
><DT
><A
NAME="GLOSS-UP"
></A
><B
><SPAN
CLASS="ACRONYM"
>UP</SPAN
></B
></DT
><DD
><P
> Uni-Processor: Non-SMP. (CONFIG_SMP=n).
</P
></DD
><DT
><A
NAME="GLOSS-USERCONTEXT"
></A
><B
>User Context</B
></DT
><DD
><P
> The kernel executing on behalf of a particular
process or kernel thread (given by the <TT
CLASS="FUNCTION"
>current()</TT
>
macro.) Not to be confused with userspace. Can be interrupted by
software or hardware interrupts.
</P
></DD
><DT
><A
NAME="GLOSS-USERSPACE"
></A
><B
>Userspace</B
></DT
><DD
><P
> A process executing its own code outside the kernel.
</P
></DD
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