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

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

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