* [BUG] Devices breaking due to CONFIG_ZONE_DEVICE
@ 2016-01-23 4:46 Sudip Mukherjee
2016-01-23 5:47 ` Dan Williams
0 siblings, 1 reply; 4+ messages in thread
From: Sudip Mukherjee @ 2016-01-23 4:46 UTC (permalink / raw)
To: Dan Williams, Christoph Hellwig
Cc: H. Peter Anvin, Ingo Molnar, Dave Hansen, Rik van Riel,
Mel Gorman, Jerome Glisse, markk, jroedel, bp, linux-kernel
Hi All,
Commit 033fbae988fc ("mm: ZONE_DEVICE for "device memory"") has
introduced CONFIG_ZONE_DEVICE while sacrificing CONFIG_ZONE_DMA.
Distributions like Ubuntu has started enabling CONFIG_ZONE_DEVICE and
thus breaking parallel port. Please have a look at
https://bugzilla.kernel.org/show_bug.cgi?id=110931 for the bug report.
Apart from parallel port I can see some sound drivers will also break.
Now what is the possible solution for this?
Regards
Sudip
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [BUG] Devices breaking due to CONFIG_ZONE_DEVICE
2016-01-23 4:46 [BUG] Devices breaking due to CONFIG_ZONE_DEVICE Sudip Mukherjee
@ 2016-01-23 5:47 ` Dan Williams
2016-01-23 6:15 ` Dan Williams
0 siblings, 1 reply; 4+ messages in thread
From: Dan Williams @ 2016-01-23 5:47 UTC (permalink / raw)
To: Sudip Mukherjee
Cc: Christoph Hellwig, H. Peter Anvin, Ingo Molnar, Dave Hansen,
Rik van Riel, Mel Gorman, Jerome Glisse, markk, Joerg Roedel,
Borislav Petkov, linux-kernel
On Fri, Jan 22, 2016 at 8:46 PM, Sudip Mukherjee
<sudipm.mukherjee@gmail.com> wrote:
> Hi All,
> Commit 033fbae988fc ("mm: ZONE_DEVICE for "device memory"") has
> introduced CONFIG_ZONE_DEVICE while sacrificing CONFIG_ZONE_DMA.
> Distributions like Ubuntu has started enabling CONFIG_ZONE_DEVICE and
> thus breaking parallel port. Please have a look at
> https://bugzilla.kernel.org/show_bug.cgi?id=110931 for the bug report.
>
> Apart from parallel port I can see some sound drivers will also break.
>
> Now what is the possible solution for this?
The tradeoff here is enabling direct-I/O for persistent memory vs
support for legacy devices.
One possible solution is to alias ZONE_DMA and ZONE_DEVICE. At early
boot if pmem is detected disable these legacy devices, or the reverse
disable DMA to persistent memory if a legacy device is detected. The
latter is a bit harder to do as I think we would want to make the
decision early during memory init before we would know if any parallel
ports or ISA sound cards are present.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [BUG] Devices breaking due to CONFIG_ZONE_DEVICE
2016-01-23 5:47 ` Dan Williams
@ 2016-01-23 6:15 ` Dan Williams
2016-01-24 9:40 ` Borislav Petkov
0 siblings, 1 reply; 4+ messages in thread
From: Dan Williams @ 2016-01-23 6:15 UTC (permalink / raw)
To: Sudip Mukherjee
Cc: Christoph Hellwig, H. Peter Anvin, Ingo Molnar, Dave Hansen,
Rik van Riel, Mel Gorman, Jerome Glisse, markk, Joerg Roedel,
Borislav Petkov, linux-kernel
On Fri, Jan 22, 2016 at 9:47 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> On Fri, Jan 22, 2016 at 8:46 PM, Sudip Mukherjee
> <sudipm.mukherjee@gmail.com> wrote:
>> Hi All,
>> Commit 033fbae988fc ("mm: ZONE_DEVICE for "device memory"") has
>> introduced CONFIG_ZONE_DEVICE while sacrificing CONFIG_ZONE_DMA.
>> Distributions like Ubuntu has started enabling CONFIG_ZONE_DEVICE and
>> thus breaking parallel port. Please have a look at
>> https://bugzilla.kernel.org/show_bug.cgi?id=110931 for the bug report.
>>
>> Apart from parallel port I can see some sound drivers will also break.
>>
>> Now what is the possible solution for this?
>
> The tradeoff here is enabling direct-I/O for persistent memory vs
> support for legacy devices.
>
> One possible solution is to alias ZONE_DMA and ZONE_DEVICE. At early
> boot if pmem is detected disable these legacy devices, or the reverse
> disable DMA to persistent memory if a legacy device is detected. The
> latter is a bit harder to do as I think we would want to make the
> decision early during memory init before we would know if any parallel
> ports or ISA sound cards are present.
...another option that might be cleaner is to teach GFP_DMA to get
memory from a different mechanism. I.e. don't use the mm-zone
infrastructure to organize that small 16MB pool of memory.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [BUG] Devices breaking due to CONFIG_ZONE_DEVICE
2016-01-23 6:15 ` Dan Williams
@ 2016-01-24 9:40 ` Borislav Petkov
0 siblings, 0 replies; 4+ messages in thread
From: Borislav Petkov @ 2016-01-24 9:40 UTC (permalink / raw)
To: Dan Williams
Cc: Sudip Mukherjee, Christoph Hellwig, H. Peter Anvin, Ingo Molnar,
Dave Hansen, Rik van Riel, Mel Gorman, Jerome Glisse, markk,
Joerg Roedel, lkml, linux-mm
+ linux-mm
On Fri, Jan 22, 2016 at 10:15:17PM -0800, Dan Williams wrote:
> On Fri, Jan 22, 2016 at 9:47 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> > On Fri, Jan 22, 2016 at 8:46 PM, Sudip Mukherjee
> > <sudipm.mukherjee@gmail.com> wrote:
> >> Hi All,
> >> Commit 033fbae988fc ("mm: ZONE_DEVICE for "device memory"") has
> >> introduced CONFIG_ZONE_DEVICE while sacrificing CONFIG_ZONE_DMA.
> >> Distributions like Ubuntu has started enabling CONFIG_ZONE_DEVICE and
> >> thus breaking parallel port. Please have a look at
> >> https://bugzilla.kernel.org/show_bug.cgi?id=110931 for the bug report.
> >>
> >> Apart from parallel port I can see some sound drivers will also break.
> >>
> >> Now what is the possible solution for this?
> >
> > The tradeoff here is enabling direct-I/O for persistent memory vs
> > support for legacy devices.
> >
> > One possible solution is to alias ZONE_DMA and ZONE_DEVICE. At early
> > boot if pmem is detected disable these legacy devices, or the reverse
> > disable DMA to persistent memory if a legacy device is detected. The
> > latter is a bit harder to do as I think we would want to make the
> > decision early during memory init before we would know if any parallel
> > ports or ISA sound cards are present.
>
> ...another option that might be cleaner is to teach GFP_DMA to get
> memory from a different mechanism. I.e. don't use the mm-zone
> infrastructure to organize that small 16MB pool of memory.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-01-23 4:46 [BUG] Devices breaking due to CONFIG_ZONE_DEVICE Sudip Mukherjee
2016-01-23 5:47 ` Dan Williams
2016-01-23 6:15 ` Dan Williams
2016-01-24 9:40 ` Borislav Petkov
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