Re: [PATCH] pci: print out DMA mask info

From: Yinghai Lu
Date: Fri Oct 10 2008 - 12:19:20 EST


On Fri, Oct 10, 2008 at 8:48 AM, Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> wrote:
> On Thursday, October 9, 2008 7:40 pm FUJITA Tomonori wrote:
>> On Thu, 9 Oct 2008 15:18:37 -0600
>>
>> Grant Grundler <grundler@xxxxxxxxxxxxxxxx> wrote:
>> > On Wed, Oct 08, 2008 at 04:02:23PM -0700, Yinghai Lu wrote:
>> > > so can find out what is DMA mask is used for pci devices in addition to
>> > > default setting.
>> >
>> > I like the idea. I don't like the additional boot time output.
>> >
>> > But I'm thinking this could be an option to lspci.
>> > lspci already knows about the /sys tree. Can PCI export the two masks
>> > (dma_mask and dma_consistent_mask) and something like "lspci -td"
>> > would dump those in a nice way?
>> >
>> > Anyone else agree?
>>
>> Agreed.
>>
>> dma_mask and dma_consistent_mask is not useful for the
>> majority. Printing them at boot time doesn't make sense for me.
>>
>> Adding under sysfs and using lspci sounds reasonable if we really need
>> these information.
>
> Another option would be to add a 'warn_dma_mask=0xxxxxxxxx' boot option that
> would trigger in the actual DMA mask setting routines. It would let you
> choose the mask you'd like to see warnings about. Yinghai?
>

another command line parameter for debug?

anyway looking at dma_mask print out is interesting..., some uses 39,
and some use 44bits...

YH
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