Re: [tlug] 4Gb RAM with 32bit kernels

[Jim Breen <jimbreen@example.com>]

Nicolas Limare <nicolas+tlug@example.com> wrote:
Jim:
>> My laptop (Compaq Presario CQ60) came with 4G of RAM, but I can only see
>> 3G of it (prolly a limitation of my 32-bit system). Is there any way I
>> can get at it from Linux for a RAM disk or something like that? Is
>> it worth doing?
>
> RAM disks are like a cached filesystem without the filesystem backend,
> so if you can only see 3Gb, I think you can't use the remaining 1Gb for
> anything, as it's just ignored by the kernel.

Naruhodo.

> But you should be able to access your 4Gb of RAM, even with a 32bit
> kernel. Maybe your distribution provides alternative kernels? PAE
> support?
> http://en.wikipedia.org/wiki/Physical_Address_Extension

Ubuntu 9.10. Yes, a PAE kernel is available. From a bit of Googling I suspect
the missing 1Gb has been snatched away by the video card.

>> As it happens, 3Gb is ample. As I write, I see I have 1.7G free, and
>> of the 1.3 used much of it is cache and buffers.
>
> I use a ramdisk for all my temporary files, it ensures everything is
> cleaned up at the next reboot. I also use it when I read a DVD and
> don't want to hear the noisy DVD motor: first copy to ramdisk, then
> read from ramdisk. So, a RAM disk can be useful, but it depends on
> your work habits.

Possibly not worth the effort for me. Especially when a ramdisk would
probably be lost during hibernation.

Thanks

Jim

-- 
Jim Breen
Adjunct Snr Research Fellow, Clayton School of IT, Monash University
Vice-president: Hawthorn Rowing Club, Treasurer: Japanese Studies Centre
Graduate student: Language Technology Group, University of Melbourne