Re: megasas stops I/O when running kernel as dom0 under xen4.1/4.2

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 19/08/11 17:37, Andreas Olsowski wrote:
> 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: 00.00.05.30 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:
>

The only change you need to make is in megasas_probe_one() in
megaraid_sas_base.c

Add a call to pci_enable_msi(pdev) immediately after the current call to
pci_set_master(pdev);

~Andrew

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com