Hello,
Looking at the thread of Interl Dual-core and 4GB a sudden thought came
to my mind: "Hey, I'm gonna upgrade my box to 4G next week too... Would
it work?"
Thus, the question - would I be able to use whole 4G RAM with dual-core
amd and kernel with SMP compiled for i686?
Thanks in advance!
Vladimir
On Thu, 27 Oct 2005, Vladimir Lazarenko wrote:
> Hello,
>
> Looking at the thread of Interl Dual-core and 4GB a sudden thought came to my
> mind: "Hey, I'm gonna upgrade my box to 4G next week too... Would it work?"
>
> Thus, the question - would I be able to use whole 4G RAM with dual-core amd
> and kernel with SMP compiled for i686?
Yes but you would only be able to malloc 3GB per process. Go with the
x86_64 kernel and that goes away. we have x86_x64's with 16GB of ram.
> Thanks in advance!
>
> Vladimir
>
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--------------------------------------------------------------------------
Joel Jaeggli Unix Consulting [email protected]
GPG Key Fingerprint: 5C6E 0104 BAF0 40B0 5BD3 C38B F000 35AB B67F 56B2
On Thu, 27 Oct 2005 23:03:07 +0200, Vladimir Lazarenko wrote
> Hello,
>
> Looking at the thread of Interl Dual-core and 4GB a sudden thought
> came to my mind: "Hey, I'm gonna upgrade my box to 4G next week
> too... Would it work?"
>
> Thus, the question - would I be able to use whole 4G RAM with dual-
> core amd and kernel with SMP compiled for i686?
I think it's google time for you both.
Both Intel and AMD mention this problem all over the place, in Windows or Linux.
http://forums.amd.com/lofiversion/index.php/t51726.html
.Alejandro
>
> Thanks in advance!
>
> Vladimir
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Open WebMail Project (http://openwebmail.org)
Vladimir Lazarenko <[email protected]> writes:
> Hello,
>
> Looking at the thread of Interl Dual-core and 4GB a sudden thought came to my
> mind: "Hey, I'm gonna upgrade my box to 4G next week too... Would it work?"
>
> Thus, the question - would I be able to use whole 4G RAM with dual-core amd and
> kernel with SMP compiled for i686?
A Dual-core is a rev-E processor so the cpu has memory hoisting support,
so it will work if your BIOS implement it properly.
Eric
On Fri, Oct 28, 2005 at 09:30:51AM -0600, Eric W. Biederman wrote:
> > Thus, the question - would I be able to use whole 4G RAM with dual-core amd and
> > kernel with SMP compiled for i686?
Why would you use a dual core AMD in 32 bit mode? Just build an x86_64
kernel.
If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
part of your memory). Remapping means you have MORE than 4 GB of physical
address, which means you need PAE to use it at all.
[email protected] writes:
> On Fri, Oct 28, 2005 at 09:30:51AM -0600, Eric W. Biederman wrote:
>> > Thus, the question - would I be able to use whole 4G RAM with dual-core amd
> and
>> > kernel with SMP compiled for i686?
>
> Why would you use a dual core AMD in 32 bit mode? Just build an x86_64
> kernel.
>
> If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
> part of your memory). Remapping means you have MORE than 4 GB of physical
> address, which means you need PAE to use it at all.
Yes, and PAE works fine with a 32bit kernel. I agree it is a silly
configuration and a 64bit kernel would use the memory more
efficiently. My basic point was that a dual-core is a recent enough
processor from AMD that it supports memory remapping. So with a
correct BIOS there should be no problems.
Eric
>>Hello,
>>
>>Looking at the thread of Interl Dual-core and 4GB a sudden thought came to my
>>mind: "Hey, I'm gonna upgrade my box to 4G next week too... Would it work?"
>>
>>Thus, the question - would I be able to use whole 4G RAM with dual-core amd and
>>kernel with SMP compiled for i686?
>
> A Dual-core is a rev-E processor so the cpu has memory hoisting support,
> so it will work if your BIOS implement it properly.
>
> Eric
Thank you!
>>>Thus, the question - would I be able to use whole 4G RAM with dual-core amd and
>>>kernel with SMP compiled for i686?
>
>
> Why would you use a dual core AMD in 32 bit mode? Just build an x86_64
> kernel.
>
> If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
> part of your memory). Remapping means you have MORE than 4 GB of physical
> address, which means you need PAE to use it at all.
Because I find my distribution's 64-bit release reasonably unstable yet? :)
Or can I somehow build an x86_64 kernel and keep using 32-bit libc?
Vladimir Lazarenko <[email protected]> writes:
>>>>Thus, the question - would I be able to use whole 4G RAM with dual-core amd
> and
>>>>kernel with SMP compiled for i686?
>> Why would you use a dual core AMD in 32 bit mode? Just build an x86_64
>> kernel.
>> If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
>> part of your memory). Remapping means you have MORE than 4 GB of physical
>> address, which means you need PAE to use it at all.
>
> Because I find my distribution's 64-bit release reasonably unstable yet? :)
>
> Or can I somehow build an x86_64 kernel and keep using 32-bit libc?
Building a x86_64 kernel is a bit of a trick on a 32bit distro.
You need an appropriate version of gcc, and binutils. But it runs
fine.
Eric
On Fri, Oct 28, 2005 at 10:13:46AM -0600, Eric W. Biederman wrote:
> > If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
> > part of your memory). Remapping means you have MORE than 4 GB of physical
> > address, which means you need PAE to use it at all.
>
> Yes, and PAE works fine with a 32bit kernel. I agree it is a silly
> configuration and a 64bit kernel would use the memory more
> efficiently. My basic point was that a dual-core is a recent enough
> processor from AMD that it supports memory remapping. So with a
> correct BIOS there should be no problems.
Earlier Opterons had remapping, too, just at the chip-select level. Even
with remapping, the memory that gets remapped gets mapped above 4 GB, so a
32 bit kernel still needs PAE to address it.
In article <[email protected]>,
Eric W. Biederman <[email protected]> wrote:
>Vladimir Lazarenko <[email protected]> writes:
>
>>>>>Thus, the question - would I be able to use whole 4G RAM with dual-core amd
>> and
>>>>>kernel with SMP compiled for i686?
>>> Why would you use a dual core AMD in 32 bit mode? Just build an x86_64
>>> kernel.
>>> If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
>>> part of your memory). Remapping means you have MORE than 4 GB of physical
>>> address, which means you need PAE to use it at all.
>>
>> Because I find my distribution's 64-bit release reasonably unstable yet? :)
>>
>> Or can I somehow build an x86_64 kernel and keep using 32-bit libc?
>
>Building a x86_64 kernel is a bit of a trick on a 32bit distro.
>You need an appropriate version of gcc, and binutils. But it runs
>fine.
I installed the 64 bit version of my distro on a small partition,
the 32 bit version on a larger partition. Then I compiled a kernel
on the 64 bit system, and installed it on the 32 bit partition.
Now I boot a 64 bit kernel for the 32 bit userland, and mount the
64-bit distribution partition under /amd64 - if I need to do
anything in 64 bit userland (like compile a new kernel) I just
chroot /amd64
Even the 64-bit binary nvidia kernel driver works fine with
a 32-bit X in userland.
Mike.
>>>If you want to use 4GB in 32 bit mode, you *need* remapping (or you lose
>>>part of your memory). Remapping means you have MORE than 4 GB of physical
>>>address, which means you need PAE to use it at all.
>>
>>Yes, and PAE works fine with a 32bit kernel. I agree it is a silly
>>configuration and a 64bit kernel would use the memory more
>>efficiently. My basic point was that a dual-core is a recent enough
>>processor from AMD that it supports memory remapping. So with a
>>correct BIOS there should be no problems.
>
>
> Earlier Opterons had remapping, too, just at the chip-select level. Even
> with remapping, the memory that gets remapped gets mapped above 4 GB, so a
> 32 bit kernel still needs PAE to address it.
Well, my BIOS had 2 types of re-mapping, H/W and S/W, i enabled H/W
remapping, compiled kernel with 64G HIGHMEM, and voila:
vlad@anarxi:~$ free
total used free shared buffers cached
Mem: 4151876 2972968 1178908 0 179008 679016
-/+ buffers/cache: 2114944 2036932
Thanks everyone!
Vladimir