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Re: [Xen-devel] megasas stops I/O when running kernel as dom0 under xen4.1/4.2

Am 19.08.2011 16:57, Andrew Cooper:

This further confirms my findings.

Do you mind intserting a call to pci_enable_msi() in the probe function
and see if that sorts out your two problem cases?

   /* Try to enable MSI-X */
   if ((instance->pdev->device != PCI_DEVICE_ID_LSI_SAS1078R) &&
       (instance->pdev->device != PCI_DEVICE_ID_LSI_SAS1078DE) &&
       (instance->pdev->device != PCI_DEVICE_ID_LSI_VERDE_ZCR) &&
!msix_disable && !pci_enable_msix(instance->pdev, &instance->msixentry, 1))
      instance->msi_flag = 1;


My device is a:
01:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 (rev 04)

and this excluded for some reason.
There are more references to this particular type of raid controller.

Can you think of a reason why msi would not work on some specific harware?

Anyway since i dont have much C-experience and wouldnt know where to put " pci_enable_msi() " exactly, i modified the above mentioned code to just do:
instance->msi_flag = 1;

I also removed "options megaraid_sas poll_mode_io=1" from the module options.

The kernel did not boot properly at that point.
Something about /dev not beeing mounted due to missing device.
Followed by udev not doing much and the system generally doing nothing that would further the bootup process.

So i went back to put that module option in again.

It still did not boot properly, here is some output:
Loading, please wait...
mount: mounting none on /dev failed: No such device
megasas: Tue. Jan. 4 17:00:00 PDT 2011
megasas: 0x1000:0x0060:0x1028:0x1f0c: bus 1:slot 0:func 0
megaraid_sas 0000:01:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
megaraid_sas 0000:01:00.0: setting latency timer to 64
megasas: FW now in Ready state
megasas: cpx is not supported.
megasas: INIT adapter done
and then came the udev failing to load something and basically nothing happened after that point.

I guess there really is a good reason not to enable msi for that type of controller.

The fact that corresponding problems from not having the module option do not happen on bare-metal isnt very helpful either. Especially when you cant test the kernel bare-metal due to the fact that it wont boot bare-metal anymore ... but i digress.

I guess an acceptable fix would be to make the module option a default for those raid controllers in the next version of the megasas modules.

glad to be of service

with best regards:

Andreas Olsowski

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