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.
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1. The APIC that is included in almost every CPU produced today (certainly all PC processors produced today) is capable of more than 15 inputs (as I understand it, there''s 256 "inputs". 2. Interupts with numbers higher than 256 are "virtual interrupts", which is a "XEN thing", and they are not REAL interrupts from hardware, but signalling within XEN to (for example) wake up another Domain. This is to the best of my understanding, and I have spent no time trying to trace, understand or research any of this, so if you''re going to use any of the above for anything serious, I suggest you do some reasearch to confirm or revise the above statements. -- Mats> -----Original Message----- > From: xen-devel-bounces@lists.xensource.com > [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of John Que > Sent: 25 August 2005 12:13 > To: Xen-devel@lists.xensource.com > Subject: [Xen-devel] IRQ range in domain 0 > > 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. > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Something to do with APIC (Advanced Programmable Interrupt Controller) I
think. Here''s the output of one system...
CPU0
0: 2548267677 local-APIC-edge timer
1: 16419 IO-APIC-edge i8042
9: 0 IO-APIC-level acpi
11: 211183161 IO-APIC-level ohci_hcd
14: 2 IO-APIC-edge ide2
169: 230697393 IO-APIC-level ide0, ide1
177: 247537790 IO-APIC-level eth0
201: 63 IO-APIC-level aic7xxx
209: 185403163 IO-APIC-level eth1
217: 126336295 IO-APIC-level eth2
NMI: 0
LOC: 2549847962
ERR: 58866
MIS: 0
> -----Original Message-----
> From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-
> bounces@lists.xensource.com] On Behalf Of John Que
> Sent: Thursday, 25 August 2005 21:13
> To: Xen-devel@lists.xensource.com
> Subject: [Xen-devel] IRQ range in domain 0
>
> 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.
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
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