From: John Que <qwejohn@gmail.com>
To: Xen-devel@lists.xensource.com
Subject: IRQ range in domain 0
Date: Thu, 25 Aug 2005 07:12:53 -0400 [thread overview]
Message-ID: <ada605fb0508250412f58312@mail.gmail.com> (raw)
Hello,
I am running Xen-Unstable on intel x386 , with one CPU ; When running
cat /proc/interrupts on Domain 0 I see the following:
CPU0
1: 1424 Phys-irq i8042
9: 0 Phys-irq acpi
14: 421055 Phys-irq ide0
15: 16 Phys-irq ide1
17: 4419 Phys-irq eth0
20: 10884 Phys-irq ohci_hcd:usb1
21: 0 Phys-irq ohci_hcd:usb2
256: 0 Dynamic-irq ctrl-if
257: 77411 Dynamic-irq timer0
258: 0 Dynamic-irq console
259: 0 Dynamic-irq net-be-dbg
NMI: 0
LOC: 0
ERR: 0
MIS: 0
can I deduce from this that the number of available physical IRQ is
higher than 15?
What is strange to me is that on an ordinary linux kernel (not a
xen-patched kernel ) , there can be up to 15 interrupts,and in all
cases I know, they are in the range 0-14.
I don't remeber I saw a phiyscal interrupt whose number is higher than 14
on a standard x386 platform.
Also according to "Unerstanding the Linux Kernel" book,chapter 4:
"Tradional PICs are implemented by connecting "in cascade" two
8259A-style external chips.Each chip can handle up to eight different
IRQ input lines. Since the INT output line of the slave PIC is
connected to the IRQ2 pin of the master PIC, the number of available
IRQ lines is limited to 15."
Any ideas?
Regards
John Que.
next reply other threads:[~2005-08-25 11:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-25 11:12 John Que [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-08-25 11:13 IRQ range in domain 0 Petersson, Mats
2005-08-25 12:14 James Harper
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