Re: [Xen-devel] [PATCH] cdb: split cdb into arch independet/dependet part

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 13 Jan 2006, at 15:46, Hollis Blanchard wrote:

> > +       /* Try to make things a little more stable by disabling
> > +          interrupts while we're here. */
> > +       local_irq_save(flags);
> ...
> > +       local_irq_restore(flags);
> Shouldn't we enter __trap_to_gdb with interrupts disabled already? 
> That's how it's done on PPC, I believe x86 can choose in the IDT, and 
> I'm sure IA64 can too?
That's true if it's a hardware-generated trap to debugger. Breakpoint 
exceptions, manual calls to trap into the debugger, etc all might enter 
the stub with ints enabled. So irqsave/restore is a reasonable 
safeguard.
> Hmm, actually, how does this interact with interrupt-driven ns16550?
The serial subsystem supports a synchronous polled mode of operation. 
You can put a COM port in polled mode by calling serial_start_sync().
 -- Keir


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel