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

Started bybasti <mailinglist@unix-solution.de>
First post2018-08-07 15:00 +0200
Last post2018-08-13 00:20 +0200
Articles 9 — 5 participants

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  Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM basti <mailinglist@unix-solution.de> - 2018-08-07 15:00 +0200
    Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM Michael Stone <mstone@debian.org> - 2018-08-07 15:10 +0200
    Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-08-07 23:00 +0200
      Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM deloptes <deloptes@gmail.com> - 2018-08-08 00:30 +0200
        Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM Michael Stone <mstone@debian.org> - 2018-08-08 01:50 +0200
          Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM basti <mailinglist@unix-solution.de> - 2018-08-08 08:30 +0200
    Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM deloptes <deloptes@gmail.com> - 2018-08-12 20:00 +0200
      Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-08-12 20:20 +0200
        Re: Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM mick crane <mick.crane@gmail.com> - 2018-08-13 00:20 +0200

#198392 — Kernel 4.9.0-7-686 Installed RAM vs. uabale RAM

Frombasti <mailinglist@unix-solution.de>
Date2018-08-07 15:00 +0200
SubjectKernel 4.9.0-7-686 Installed RAM vs. uabale RAM
Message-ID<wk9KF-JR-1@gated-at.bofh.it>
Hello, I have a system with Kernel 4.9.0-7-686, installed RAM are 3x 1GB
but free -m only show 2GB.

Whats wrong here?

# free -m
              total        used        free      shared  buff/cache  
available
Mem:           2018         203        1204          25        
610        1569
Swap:          8191           0        8191


# dmidecode -t 17
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.4 present.

Handle 0x0029, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x0028
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 1024 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM-1A
    Bank Locator: Not Specified
    Type: DDR2
    Type Detail: Synchronous
    Speed: 800 MHz
    Manufacturer: Not Specified
    Serial Number: Not Specified
    Asset Tag: Not Specified
    Part Number: Not Specified

Handle 0x002A, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x0028
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 1024 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM-2A
    Bank Locator: Not Specified
    Type: DDR2
    Type Detail: Synchronous
    Speed: 800 MHz
    Manufacturer: Not Specified
    Serial Number: Not Specified
    Asset Tag: Not Specified
    Part Number: Not Specified

Handle 0x002B, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x0028
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 1024 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM-1B
    Bank Locator: Not Specified
    Type: DDR2
    Type Detail: Synchronous
    Speed: 800 MHz
    Manufacturer: Not Specified
    Serial Number: Not Specified
    Asset Tag: Not Specified
    Part Number: Not Specified

Handle 0x002C, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x0028
    Error Information Handle: No Error
    Total Width: Unknown
    Data Width: Unknown
    Size: No Module Installed
    Form Factor: DIMM
    Set: None
    Locator: DIMM-2B
    Bank Locator: Not Specified
    Type: DDR2
    Type Detail: Synchronous
    Speed: 800 MHz
    Manufacturer: Not Specified
    Serial Number: Not Specified
    Asset Tag: Not Specified
    Part Number: Not Specified


As I know 6868 can address 4GB RAM

Best Regards,

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#198397

FromMichael Stone <mstone@debian.org>
Date2018-08-07 15:10 +0200
Message-ID<wk9Un-13f-49@gated-at.bofh.it>
In reply to#198392
On Tue, Aug 07, 2018 at 02:53:18PM +0200, basti wrote:
>Hello, I have a system with Kernel 4.9.0-7-686, installed RAM are 3x 1GB
>but free -m only show 2GB.
>
>Whats wrong here?

Install a -pae kernel.

Mike Stone

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#198436

FromPascal Hambourg <pascal@plouf.fr.eu.org>
Date2018-08-07 23:00 +0200
Message-ID<wkhfc-5uc-13@gated-at.bofh.it>
In reply to#198392
Le 07/08/2018 à 14:53, basti a écrit :
> Hello, I have a system with Kernel 4.9.0-7-686, installed RAM are 3x 1GB
> but free -m only show 2GB.
> 
> Whats wrong here?
(...)
> As I know 686 can address 4GB RAM

No. It can address 4 GiB memory space. Memory space does not contain 
only RAM, it is also used to address system devices such as the graphics 
controller. The part of the memory address space which is reserved for 
system devices is often called "PCI hole". Some motherboards reserve a 
very large amount of address space for the PCI hole, up to 2 GiB as I 
have already seen. When you are lucky, the RAM which cannot be mapped in 
the PCI hole can be remapped beyond the 4 GiB boundary. Sometimes it 
requires to enable an option in the BIOS settings. But you need a 
686-pae or amd64 kernel to use RAM beyond 4 GiB, as Michael pointed out.

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#198441

Fromdeloptes <deloptes@gmail.com>
Date2018-08-08 00:30 +0200
Message-ID<wkiEi-6v4-5@gated-at.bofh.it>
In reply to#198436
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?

regards

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#198442

FromMichael Stone <mstone@debian.org>
Date2018-08-08 01:50 +0200
Message-ID<wkjTH-7cv-7@gated-at.bofh.it>
In reply to#198441
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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#198447

Frombasti <mailinglist@unix-solution.de>
Date2018-08-08 08:30 +0200
Message-ID<wkq8N-2Ps-1@gated-at.bofh.it>
In reply to#198442
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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#198671

Fromdeloptes <deloptes@gmail.com>
Date2018-08-12 20:00 +0200
Message-ID<wm2OJ-4fi-3@gated-at.bofh.it>
In reply to#198392
Dale Forsyth wrote:

> Hello, I have a system with Kernel 4.9.0-7-686, installed RAM are 3x 1GB
> but free -m only show 2GB.

hyperactively posting is bad ting - the question was answered coupe of days
ago.
The answer was install PAE kernel.

regards

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#198675

FromPascal Hambourg <pascal@plouf.fr.eu.org>
Date2018-08-12 20:20 +0200
Message-ID<wm385-4AR-1@gated-at.bofh.it>
In reply to#198671
Le 12/08/2018 à 19:53, deloptes a écrit :
> Dale Forsyth wrote:
> 
>> Hello, I have a system with Kernel 4.9.0-7-686, installed RAM are 3x 1GB
>> but free -m only show 2GB.

Please pay attention when reading, replying and quoting. "Dale Forsyth" 
did not write this part. He/she/it just replied to random threads to 
send spam.

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#198680

Frommick crane <mick.crane@gmail.com>
Date2018-08-13 00:20 +0200
Message-ID<wm6Sl-6ML-3@gated-at.bofh.it>
In reply to#198675
On 2018-08-12 19:17, Pascal Hambourg wrote:
> Le 12/08/2018 à 19:53, deloptes a écrit :
>> Dale Forsyth wrote:
>> 
>>> Hello, I have a system with Kernel 4.9.0-7-686, installed RAM are 3x 
>>> 1GB
>>> but free -m only show 2GB.
> 
> Please pay attention when reading, replying and quoting. "Dale
> Forsyth" did not write this part. He/she/it just replied to random
> threads to send spam.

I was going to say something but I was going through the process count 
to a hundred, walk around the room tapping your head and rubbing your 
belly and so on.

mick
-- 
Key ID    4BFEBB31

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