Re: [PATCH 1/1] 3ware add MSI support

[Boaz Harrosh <bharrosh@panasas.com>]

James Bottomley wrote:
> On Tue, 2008-07-22 at 19:47 -0600, Matthew Wilcox wrote:
>> On Tue, Jul 22, 2008 at 04:36:32PM -0700, adam radford wrote:
>>> This patch for the 3w-9xxx scsi driver applies on top of the
>>> BKL-pushdown changes in -git9.
>>>
>>> This patch does the following:
>>>
>>> - Increase max AENs drained to 256.
>>> - Add MSI support and "use_msi" module parameter.
>>> - Fix bug in twa_get_param() on 4GB+.
>>> - Use pci_resource_len() for ioremap().
>> Is there a reason you default use_msi to off?  I would have thought
>> you'd want to enable it as widely as possible.
> 
> Hardly ... just look at our LSI fiasco with globally enabling them.
> 
> Right at the moment, due to motherboard bugs, it looks like global
> enabling of MSI by default would produce a significant increase in "my
> system doesn't boot" type bugs.
> 
> I asked Jesse if we could actually get better recognition of
> motherboards with MSI problems in pci/quirks.c to forestall some of
> this, but it seems to be a hard problem.  I've cc'd the PCI list in case
> they have better suggestions.
> 
> James
> 

This seems to be a general problem. Maybe there should be an LSI_SYSTEM_DEFAULT
kind of parameter or function, that will enable LSI if it is default for the
system on all supporting drivers. This way a user can configure LSI=on for all
drivers in one place instead of configuring each driver individually.

Boaz