remap_pfn_range() not suitable for physical RAM?

remap_pfn_range() not suitable for physical RAM?

[Frank Mehnert]

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Hi,

since 2.6.29-rcX it seems to be not allowed anymore to use
remap_pfn_range() to remap physical RAM to userland. This restriction
applies only if CONFIG_X86_PAT is enabled. It seems that vm_insert_page()
does not have this restriction. Am I correct? And what is the reason
for this restriction?

Kind regards,

Frank
-- 
Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/

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Re: remap_pfn_range() not suitable for physical RAM?

[Frank Mehnert]

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Hi,

sorry for re-posting this message and sorry for addressing you directly.
Perhaps you can help me again or can you give me a pointer for a proper
documentation of the various *remap* and *vm_insert* functions:

On Wednesday 04 March 2009, Frank Mehnert wrote:
> since 2.6.29-rcX it seems to be not allowed anymore to use
> remap_pfn_range() to remap physical RAM to userland. This restriction
> applies only if CONFIG_X86_PAT is enabled. It seems that vm_insert_page()
> does not have this restriction. Am I correct? And what is the reason
> for this restriction?

Kind regards,

Frank
-- 
Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/

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RE: remap_pfn_range() not suitable for physical RAM?

[Pallipadi, Venkatesh]

Frank,

Patch here should eliminate the restriction.
http://marc.info/?l=linux-kernel&m=123664923030126&w=1

Thanks,
Venki
 

>-----Original Message-----
>From: linux-kernel-owner@vger.kernel.org 
>[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Frank Mehnert
>Sent: Tuesday, March 10, 2009 1:04 AM
>To: linux-kernel@vger.kernel.org
>Cc: peterz@infradead.org; Siddha, Suresh B
>Subject: Re: remap_pfn_range() not suitable for physical RAM?
>
>Hi,
>
>sorry for re-posting this message and sorry for addressing you 
>directly.
>Perhaps you can help me again or can you give me a pointer for a proper
>documentation of the various *remap* and *vm_insert* functions:
>
>On Wednesday 04 March 2009, Frank Mehnert wrote:
>> since 2.6.29-rcX it seems to be not allowed anymore to use
>> remap_pfn_range() to remap physical RAM to userland. This restriction
>> applies only if CONFIG_X86_PAT is enabled. It seems that 
>vm_insert_page()
>> does not have this restriction. Am I correct? And what is the reason
>> for this restriction?
>
>Kind regards,
>
>Frank
>-- 
>Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/
>

Re: remap_pfn_range() not suitable for physical RAM?

[Frank Mehnert]

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Venki,

thanks for your reply. May I ask anyway why this check is done in 
remap_pfn_range() and vm_insert_pfn() but not in vm_insert_page()?

Kind regards,

Frank

On Tuesday 10 March 2009, Pallipadi, Venkatesh wrote:
> Frank,
>
> Patch here should eliminate the restriction.
> http://marc.info/?l=linux-kernel&m=123664923030126&w=1
>
> Thanks,
> Venki
>
> >-----Original Message-----
> >From: linux-kernel-owner@vger.kernel.org
> >[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Frank Mehnert
> >Sent: Tuesday, March 10, 2009 1:04 AM
> >To: linux-kernel@vger.kernel.org
> >Cc: peterz@infradead.org; Siddha, Suresh B
> >Subject: Re: remap_pfn_range() not suitable for physical RAM?
> >
> >Hi,
> >
> >sorry for re-posting this message and sorry for addressing you
> >directly.
> >Perhaps you can help me again or can you give me a pointer for a proper
> >documentation of the various *remap* and *vm_insert* functions:
> >
> >On Wednesday 04 March 2009, Frank Mehnert wrote:
> >> since 2.6.29-rcX it seems to be not allowed anymore to use
> >> remap_pfn_range() to remap physical RAM to userland. This restriction
> >> applies only if CONFIG_X86_PAT is enabled. It seems that
> >
> >vm_insert_page()
> >
> >> does not have this restriction. Am I correct? And what is the reason
> >> for this restriction?
> >
> >Kind regards,
> >
> >Frank
> >--
> >Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/
> >--
>
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/



-- 
Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/

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Re: remap_pfn_range() not suitable for physical RAM?

[Pallipadi, Venkatesh]

Frank,

The track and untrack is keeping track of memory type for non-RAM
regions and making sure that the type is in sync for various mappings
for such addresses. We are not tracking the RAM pages today, so
vm_insert_page does not have this. vm_insert_mixed is also not covered
today, as we deferred that and tracking of RAM pages into our next set
of changes.

Thanks,
Venki

On Fri, 2009-03-13 at 08:00 -0700, Frank Mehnert wrote:
> Venki,
> 
> thanks for your reply. May I ask anyway why this check is done in 
> remap_pfn_range() and vm_insert_pfn() but not in vm_insert_page()?
> 
> Kind regards,
> 
> Frank
> 
> On Tuesday 10 March 2009, Pallipadi, Venkatesh wrote:
> > Frank,
> >
> > Patch here should eliminate the restriction.
> > http://marc.info/?l=linux-kernel&m=123664923030126&w=1
> >
> > Thanks,
> > Venki
> >
> > >-----Original Message-----
> > >From: linux-kernel-owner@vger.kernel.org
> > >[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Frank Mehnert
> > >Sent: Tuesday, March 10, 2009 1:04 AM
> > >To: linux-kernel@vger.kernel.org
> > >Cc: peterz@infradead.org; Siddha, Suresh B
> > >Subject: Re: remap_pfn_range() not suitable for physical RAM?
> > >
> > >Hi,
> > >
> > >sorry for re-posting this message and sorry for addressing you
> > >directly.
> > >Perhaps you can help me again or can you give me a pointer for a proper
> > >documentation of the various *remap* and *vm_insert* functions:
> > >
> > >On Wednesday 04 March 2009, Frank Mehnert wrote:
> > >> since 2.6.29-rcX it seems to be not allowed anymore to use
> > >> remap_pfn_range() to remap physical RAM to userland. This restriction
> > >> applies only if CONFIG_X86_PAT is enabled. It seems that
> > >
> > >vm_insert_page()
> > >
> > >> does not have this restriction. Am I correct? And what is the reason
> > >> for this restriction?
> > >
> > >Kind regards,
> > >
> > >Frank
> > >--
> > >Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/
> > >--
> >
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 
> 
> 

Re: remap_pfn_range() not suitable for physical RAM?

[Frank Mehnert]

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Venki,

thanks for these explanations. So vm_insert_page() is only meant for
RAM pages and remap_pfn_range() can be used for any mappings (inclusive
I/O memory), is that right?

Thanks,

Frank

On Friday 13 March 2009, Pallipadi, Venkatesh wrote:
> Frank,
>
> The track and untrack is keeping track of memory type for non-RAM
> regions and making sure that the type is in sync for various mappings
> for such addresses. We are not tracking the RAM pages today, so
> vm_insert_page does not have this. vm_insert_mixed is also not covered
> today, as we deferred that and tracking of RAM pages into our next set
> of changes.
>
> Thanks,
> Venki
>
> On Fri, 2009-03-13 at 08:00 -0700, Frank Mehnert wrote:
> > Venki,
> >
> > thanks for your reply. May I ask anyway why this check is done in
> > remap_pfn_range() and vm_insert_pfn() but not in vm_insert_page()?
> >
> > Kind regards,
> >
> > Frank
> >
> > On Tuesday 10 March 2009, Pallipadi, Venkatesh wrote:
> > > Frank,
> > >
> > > Patch here should eliminate the restriction.
> > > http://marc.info/?l=linux-kernel&m=123664923030126&w=1
> > >
> > > Thanks,
> > > Venki
> > >
> > > >-----Original Message-----
> > > >From: linux-kernel-owner@vger.kernel.org
> > > >[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Frank Mehnert
> > > >Sent: Tuesday, March 10, 2009 1:04 AM
> > > >To: linux-kernel@vger.kernel.org
> > > >Cc: peterz@infradead.org; Siddha, Suresh B
> > > >Subject: Re: remap_pfn_range() not suitable for physical RAM?
> > > >
> > > >Hi,
> > > >
> > > >sorry for re-posting this message and sorry for addressing you
> > > >directly.
> > > >Perhaps you can help me again or can you give me a pointer for a
> > > > proper documentation of the various *remap* and *vm_insert*
> > > > functions:
> > > >
> > > >On Wednesday 04 March 2009, Frank Mehnert wrote:
> > > >> since 2.6.29-rcX it seems to be not allowed anymore to use
> > > >> remap_pfn_range() to remap physical RAM to userland. This
> > > >> restriction applies only if CONFIG_X86_PAT is enabled. It seems that
> > > >
> > > >vm_insert_page()
> > > >
> > > >> does not have this restriction. Am I correct? And what is the reason
> > > >> for this restriction?
> > > >
> > > >Kind regards,
> > > >
> > > >Frank
> > > >--
> > > >Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/
> > > >--
> > >
> > > To unsubscribe from this list: send the line "unsubscribe linux-kernel"
> > > in the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > > Please read the FAQ at  http://www.tux.org/lkml/
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/



-- 
Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/

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