Yes. We need something like that since one must now 'enable' the
device to have its final IRQ routing established. This has created
dire consequences for existin drivers.
However, I have the following comments about the patch.
+ if (!(pci_command & PCI_COMMAND_INTX_DISABLE)) {
|
|
|___ This is never needed. Just read the register,
do your thing, then write it back.
On Fri, 3 Jun 2005, Vivek Goyal wrote:
Hi,
In kdump, sometimes, general driver initialization issues seems to be cropping
in second kernel due to devices not being shutdown during crash and these
devices are sending interrupts while second kernel is booting and drivers are
not expecting any interrupts yet.
In some cases, we are observing a storm of interrupts while second kernel
is booting and kernel disables that irq line. May be the case of stuck irq
line because it is shared level triggered irq and there is no driver
loaded for the device.
So, we need something generic which disables interrupt generation from device
until a driver has been registered for that device and driver is ready to
receive the interrupts. PCI specifications (ver 2.3 onwards), have introduced
interrupt disable bit in command register to disable interrupt generation
from the device. This can become handy here. In capture kernel, traverse all
the PCI devices, disable interrupt generation. Enable the interrupt generation
back once the driver for that device registers. May be after the probe handler
has run. In probe handler, driver can reset the device or register for irq so
that it can handle any interrupt from the device after that.
Greg mentioned that there are reasons that we can not disable all pci
interrupts. Meanwhile I am going through archives to find more about it.
In previous conversations, Alan Stern had raised the issue of console also
not working if interrupts are disabled on all the devices. I am not sure
but this should be working at least for serial consoles and vga text consoles.
May be sufficient to capture the dump.
Attached is a hack patch which is by no means complete. I have got one machine
which has got some PCI 2.3 compliant hardware. After applying this hack this
problem does not occur atleast on this machine. Attached is the serial console
log which shows one kind of problem due to unwanted interrupts.
Bugme 4631 and 4573 are two more instances of driver initialization failure
in second kernel.
---
o In kdump, devices are not shutdown/reset after a crash and this leads to
various driver initialization failures while second kernel is booting.
Most of them seem to be happening due to the fact that system/driver
is receiving the interrupts from device when it is not prepared to do so.
o This patch tries to solve the problem by disabling the interrupts at
PCI level for all the devices. These interrupts are enabled back once the
driver for that device registers. Currenty this enabling and disabling
is done only in dump capture kernel.
o This is for devices compliant to PCI specification v2.3 or higher.
Signed-off-by: Vivek Goyal <[email protected]>
---
linux-2.6.12-rc5-mm1-16M-root/drivers/pci/pci-driver.c | 3 +
linux-2.6.12-rc5-mm1-16M-root/drivers/pci/pci.c | 4 ++
linux-2.6.12-rc5-mm1-16M-root/include/linux/pci.h | 33 +++++++++++++++++
3 files changed, 39 insertions(+), 1 deletion(-)
diff -puN drivers/pci/pci.c~kdump-pci-interrupt-disable drivers/pci/pci.c
--- linux-2.6.12-rc5-mm1-16M/drivers/pci/pci.c~kdump-pci-interrupt-disable 2005-06-03 14:35:26.000000000 +0530
+++ linux-2.6.12-rc5-mm1-16M-root/drivers/pci/pci.c 2005-06-03 15:59:19.000000000 +0530
@@ -823,6 +823,10 @@ static int __devinit pci_init(void)
while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
pci_fixup_device(pci_fixup_final, dev);
+
+ /* A hack to disable interrupts from all PCI devices in
+ * capture kernel. */
+ pci_disable_device_intx(dev);
}
return 0;
}
diff -puN drivers/pci/pci-driver.c~kdump-pci-interrupt-disable drivers/pci/pci-driver.c
--- linux-2.6.12-rc5-mm1-16M/drivers/pci/pci-driver.c~kdump-pci-interrupt-disable 2005-06-03 14:35:26.000000000 +0530
+++ linux-2.6.12-rc5-mm1-16M-root/drivers/pci/pci-driver.c 2005-06-03 14:35:26.000000000 +0530
@@ -248,7 +248,8 @@ static int pci_device_probe(struct devic
error = __pci_device_probe(drv, pci_dev);
if (error)
pci_dev_put(pci_dev);
-
+ else
+ pci_enable_device_intx(pci_dev);
return error;
}
diff -puN include/linux/pci.h~kdump-pci-interrupt-disable include/linux/pci.h
--- linux-2.6.12-rc5-mm1-16M/include/linux/pci.h~kdump-pci-interrupt-disable 2005-06-03 14:35:26.000000000 +0530
+++ linux-2.6.12-rc5-mm1-16M-root/include/linux/pci.h 2005-06-03 16:06:32.000000000 +0530
@@ -901,6 +901,39 @@ extern void pci_disable_msix(struct pci_
extern void msi_remove_pci_irq_vectors(struct pci_dev *dev);
#endif
+#ifdef CONFIG_CRASH_DUMP
+static inline int pci_enable_device_intx(struct pci_dev *dev)
+{
+ u16 pci_command;
+
+ /* Enable Interrupt generation if not already enabled */
+ pci_read_config_word(dev, PCI_COMMAND, &pci_command);
+ if (pci_command & PCI_COMMAND_INTX_DISABLE) {
+ pci_command &= ~PCI_COMMAND_INTX_DISABLE;
+ pci_write_config_word(dev, PCI_COMMAND, pci_command);
+ }
+ return 0;
+}
+
+static inline int pci_disable_device_intx(struct pci_dev *dev)
+{
+ u16 pci_command;
+
+ /* Disable Interrupt generation if not already disabled */
+ pci_read_config_word(dev, PCI_COMMAND, &pci_command);
+ if (!(pci_command & PCI_COMMAND_INTX_DISABLE)) {
+ pci_command |= PCI_COMMAND_INTX_DISABLE;
+ pci_write_config_word(dev, PCI_COMMAND, pci_command);
+ }
+ return 0;
+}
+#else
+static inline int pci_enable_device_intx(struct pci_dev *dev)
+{ return 0; }
+static inline int pci_disable_device_intx(struct pci_dev *dev)
+{ return 0; }
+#endif /* CONFIG_CRASH_DUMP */
+
#endif /* CONFIG_PCI */
/* Include architecture-dependent settings and functions */
_
Cheers,
Dick Johnson
Penguin : Linux version 2.6.11.9 on an i686 machine (5537.79 BogoMips).
Notice : All mail here is now cached for review by Dictator Bush.
98.36% of all statistics are fiction.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
