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Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM

Thanks a lot for all infos right now. I will try a PAE Kernel next week.

best regards

On 08.08.2018 01:48, Michael Stone wrote:
> On Wed, Aug 08, 2018 at 12:25:14AM +0200, deloptes wrote:
>> Pascal Hambourg wrote:
>>>  But you need a
>>> 686-pae or amd64 kernel to use RAM beyond 4 GiB, as Michael pointed out.
>> but he has 3GB and machine sees only 2 - is it because kernel is not pae?
>> I was thinking that 686 system can see (and use) around 3GB and with some
>> trick above, but in case of 4GB it did not make any sense from technical
>> point of view, because much of it is lost for reserved mapping tables
>> (AFAIR). So mem is optimal on that machine, but why it can see only 2
>> of 3?
>> Is one GB shared with graphics controller?
> Short answer is yes, all 3GB should show up. Why isn't it? No idea.
> dmesg would help, lscpu would help, knowing whether all 3GB is seen in
> the system's bios would help. PAE kernel might help, and performance
> with 3GB RAM and no PAE will be really terrible anyway. The only reason
> to run a non-PAE kernel would be if the CPU is too old to support PAE.
> (In which case there may be any number of reasons why things are flaky
> on 15 or 20 year old hardware.)
> If this is a really, really old machine and just an experiment, carry
> on. With reasonably modern hardware the right answer for >1G RAM is an
> amd64 kernel. If you have an (unusual) need to run an i386 userspace you
> can install the amd64 kernel on i386 system. All of the options for
> running >1G on 32 bit kernel have pretty severe performance impact.
> It's possible that memory has been reserved for an on-board GPU, but I'm
> having trouble wrapping my head around the idea of a machine that
> memory-limited using a gig of video memory. dmesg would help understand
> that. I lean toward suspecting the chipset just doesn't support >2G, but
> knowing what the BIOS reports would clear that up.
> Mike Stone

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