* [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
end of thread, other threads:[~2016-01-24 9:41 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 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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