* How to add more memory?
@ 2004-01-21 21:58 Nils Larson
2004-01-21 21:58 ` Nils Larson
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Nils Larson @ 2004-01-21 21:58 UTC (permalink / raw)
To: linux-mips
Hi,
We currently have a mips platform running Linux with 256MB of
RAM starting at 0x8000_0000. We would like to add an additional
1GB of RAM, maybe starting at 0x4000_0000, that would be used
for user apps (user virtual memory). The memory map is:
0x8000_0000 - 256MB RAM
0xA000_0000 - uncached version of the same 256MB
0xB000_0000 - PCI memory windows.
This is a diskless setup booting from a ramdisk.
So, the (sort of newbie) questions are:
1. How do we tell Linux to use the new memory?
2. Is this feasible?
3. Is there a better way to add more memory?
We need more space for user data.
Thanks,
Nils
^ permalink raw reply [flat|nested] 6+ messages in thread* How to add more memory?
2004-01-21 21:58 How to add more memory? Nils Larson
@ 2004-01-21 21:58 ` Nils Larson
2004-01-21 22:37 ` Jun Sun
2004-01-22 0:28 ` Ralf Baechle
2 siblings, 0 replies; 6+ messages in thread
From: Nils Larson @ 2004-01-21 21:58 UTC (permalink / raw)
To: linux-mips
Hi,
We currently have a mips platform running Linux with 256MB of
RAM starting at 0x8000_0000. We would like to add an additional
1GB of RAM, maybe starting at 0x4000_0000, that would be used
for user apps (user virtual memory). The memory map is:
0x8000_0000 - 256MB RAM
0xA000_0000 - uncached version of the same 256MB
0xB000_0000 - PCI memory windows.
This is a diskless setup booting from a ramdisk.
So, the (sort of newbie) questions are:
1. How do we tell Linux to use the new memory?
2. Is this feasible?
3. Is there a better way to add more memory?
We need more space for user data.
Thanks,
Nils
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How to add more memory?
2004-01-21 21:58 How to add more memory? Nils Larson
2004-01-21 21:58 ` Nils Larson
@ 2004-01-21 22:37 ` Jun Sun
2004-01-22 0:28 ` Ralf Baechle
2 siblings, 0 replies; 6+ messages in thread
From: Jun Sun @ 2004-01-21 22:37 UTC (permalink / raw)
To: Nils Larson; +Cc: linux-mips, jsun
On Wed, Jan 21, 2004 at 03:58:24PM -0600, Nils Larson wrote:
> Hi,
> We currently have a mips platform running Linux with 256MB of
> RAM starting at 0x8000_0000. We would like to add an additional
> 1GB of RAM, maybe starting at 0x4000_0000, that would be used
> for user apps (user virtual memory). The memory map is:
> 0x8000_0000 - 256MB RAM
> 0xA000_0000 - uncached version of the same 256MB
> 0xB000_0000 - PCI memory windows.
> This is a diskless setup booting from a ramdisk.
> So, the (sort of newbie) questions are:
> 1. How do we tell Linux to use the new memory?
> 2. Is this feasible?
> 3. Is there a better way to add more memory?
> We need more space for user data.
> Thanks,
> Nils
>
People have done this before in 2.4 with CONFIG_HIGHMEM.
See arch/mips/sibyte/cfe/setup.c for more details.
However, if the CPU suffers from virtual aliasing problem, I
think this won't work at all.
I think that is pretty much only way to get more RAM
in 32bit system. With 64bit kernel of course you don't have
any problems at all.
Jun
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How to add more memory?
2004-01-21 21:58 How to add more memory? Nils Larson
2004-01-21 21:58 ` Nils Larson
2004-01-21 22:37 ` Jun Sun
@ 2004-01-22 0:28 ` Ralf Baechle
2 siblings, 0 replies; 6+ messages in thread
From: Ralf Baechle @ 2004-01-22 0:28 UTC (permalink / raw)
To: Nils Larson
On Wed, Jan 21, 2004 at 03:58:24PM -0600, Nils Larson wrote:
> We currently have a mips platform running Linux with 256MB of
> RAM starting at 0x8000_0000. We would like to add an additional
> 1GB of RAM, maybe starting at 0x4000_0000, that would be used
> for user apps (user virtual memory). The memory map is:
> 0x8000_0000 - 256MB RAM
> 0xA000_0000 - uncached version of the same 256MB
> 0xB000_0000 - PCI memory windows.
> This is a diskless setup booting from a ramdisk.
> So, the (sort of newbie) questions are:
> 1. How do we tell Linux to use the new memory?
> 2. Is this feasible?
> 3. Is there a better way to add more memory?
> We need more space for user data.
I wrote the highmem code for Linux/MIPS. It's currently limited
to processor configurations that don't suffer from virtual aliases but
that limitation can be removed; depending of your application and hardware
that may be anywhere from trivial to hard. What is your processor?
Ralf
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: How to add more memory?
@ 2004-01-23 15:14 Nils Larson
2004-01-23 15:14 ` Nils Larson
0 siblings, 1 reply; 6+ messages in thread
From: Nils Larson @ 2004-01-23 15:14 UTC (permalink / raw)
To: Ralf Baechle, linux-mips
Ralf,
That's for responding.
We're using the RM7000A on one platform and the RM7065C on another.
Also, how exactly does highmem work? I can't seem to find a description
of how highmem works (without reading code). I've read comments about hits
on performance using this. How much of a hit is it? Is it
possible to DMA to this memory?
Thanks,
Nils
-----Original Message-----
From: Ralf Baechle [mailto:ralf@linux-mips.org]
Sent: Wednesday, January 21, 2004 6:28 PM
To: Nils Larson
Subject: Re: How to add more memory?
On Wed, Jan 21, 2004 at 03:58:24PM -0600, Nils Larson wrote:
> We currently have a mips platform running Linux with 256MB of
> RAM starting at 0x8000_0000. We would like to add an additional
> 1GB of RAM, maybe starting at 0x4000_0000, that would be used
> for user apps (user virtual memory). The memory map is:
> 0x8000_0000 - 256MB RAM
> 0xA000_0000 - uncached version of the same 256MB
> 0xB000_0000 - PCI memory windows.
> This is a diskless setup booting from a ramdisk.
> So, the (sort of newbie) questions are:
> 1. How do we tell Linux to use the new memory?
> 2. Is this feasible?
> 3. Is there a better way to add more memory?
> We need more space for user data.
I wrote the highmem code for Linux/MIPS. It's currently limited
to processor configurations that don't suffer from virtual aliases but
that limitation can be removed; depending of your application and hardware
that may be anywhere from trivial to hard. What is your processor?
Ralf
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: How to add more memory?
2004-01-23 15:14 Nils Larson
@ 2004-01-23 15:14 ` Nils Larson
0 siblings, 0 replies; 6+ messages in thread
From: Nils Larson @ 2004-01-23 15:14 UTC (permalink / raw)
To: Ralf Baechle, linux-mips
Ralf,
That's for responding.
We're using the RM7000A on one platform and the RM7065C on another.
Also, how exactly does highmem work? I can't seem to find a description
of how highmem works (without reading code). I've read comments about hits
on performance using this. How much of a hit is it? Is it
possible to DMA to this memory?
Thanks,
Nils
-----Original Message-----
From: Ralf Baechle [mailto:ralf@linux-mips.org]
Sent: Wednesday, January 21, 2004 6:28 PM
To: Nils Larson
Subject: Re: How to add more memory?
On Wed, Jan 21, 2004 at 03:58:24PM -0600, Nils Larson wrote:
> We currently have a mips platform running Linux with 256MB of
> RAM starting at 0x8000_0000. We would like to add an additional
> 1GB of RAM, maybe starting at 0x4000_0000, that would be used
> for user apps (user virtual memory). The memory map is:
> 0x8000_0000 - 256MB RAM
> 0xA000_0000 - uncached version of the same 256MB
> 0xB000_0000 - PCI memory windows.
> This is a diskless setup booting from a ramdisk.
> So, the (sort of newbie) questions are:
> 1. How do we tell Linux to use the new memory?
> 2. Is this feasible?
> 3. Is there a better way to add more memory?
> We need more space for user data.
I wrote the highmem code for Linux/MIPS. It's currently limited
to processor configurations that don't suffer from virtual aliases but
that limitation can be removed; depending of your application and hardware
that may be anywhere from trivial to hard. What is your processor?
Ralf
^ permalink raw reply [flat|nested] 6+ messages in thread
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2004-01-21 21:58 How to add more memory? Nils Larson
2004-01-21 21:58 ` Nils Larson
2004-01-21 22:37 ` Jun Sun
2004-01-22 0:28 ` Ralf Baechle
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2004-01-23 15:14 Nils Larson
2004-01-23 15:14 ` Nils Larson
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