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Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?

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Old 07-11-2008, 10:30 AM   #1
a_patch
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Registered: Jun 2008
Distribution: Mandriva Spring 2008.1 - 2.6.24.4-laptop-1mnt
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Mandriva 2008.1 3GB RAM instead 4GB


Hi everybody,

I have problem with my memory. I checked in my laptop spec and there is info about 4GB RAM support. I looked in google too, and there was three option's or recompile kernel with HIGHMEM option, or change BIOS "Memory hole remapping" option, or install kernel-server. But:

1. I have 64bit processor and 64bit version of Linux Mandriva 2008.1 with kernel 2.6.24.4-laptop-1mnb, but there is no option like HIGHMEM in my menuconfig and in /boot/config, so I can change it in my kernel.

2. I have laptop Toshiba Equium A100 series and BIOS is really basic. There is nothing like "memory hole remapping" but in BIOS I see 4GB RAM. Here is specification.

3. I tried to install kernel-server. No changes.

I still have 3015 MB in my system. I know, that 32bit systems should see max 3GB, but why my 64bit Linux see only three gigs?

Is there some way to find those 1GB of RAM?

With best regards
a_patch
 
Old 07-12-2008, 05:59 AM   #2
watcher69b
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can your system BIOS recognise memory above 3gb? when the laptop starts up do you see it in the POST?
 
Old 07-12-2008, 07:03 AM   #3
johnsfine
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Quote:
Originally Posted by a_patch View Post
2. I have laptop Toshiba Equium A100 series and BIOS is really basic. There is nothing like "memory hole remapping" but in BIOS I see 4GB RAM.
You should verify that the BIOS is failing to report the extra memory to Linux.

Try (fairly soon after rebooting)
Code:
dmesg | less
The output should include the map of memory passed from the BIOS to the OS. Mine looks like this:
Code:
BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 000000000009f800 (usable)
 BIOS-e820: 000000000009f800 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 00000000bbee0000 (usable)
 BIOS-e820: 00000000bbee0000 - 00000000bbee3000 (ACPI NVS)
 BIOS-e820: 00000000bbee3000 - 00000000bbef0000 (ACPI data)
 BIOS-e820: 00000000bbef0000 - 00000000bbf00000 (reserved)
 BIOS-e820: 00000000bc000000 - 00000000c0000000 (reserved)
 BIOS-e820: 00000000f0000000 - 00000000f2000000 (reserved)
 BIOS-e820: 00000000fec00000 - 0000000100000000 (reserved)
 BIOS-e820: 0000000100000000 - 0000000240000000 (usable)
The first and fourth lines show I have almost 3 GB of RAM within the first 4GB address space. The last line shows I have 5GB of RAM above the first 4GB address. So almost all of my 8GB is usable.

If your BIOS ram map does show the full 4GB (very unlikely based on what you already posted) that would imply you're not running the version of the Linux kernel you think you're running and the correction would be there.

If (as we expect) it shows 3GB ram in the first 4GB of address space and nothing above that, then the main problem is in the BIOS.

Look though the entire BIOS menu system for anything related to either memory or communication with the OS. Often there is a confusing choice about how the BIOS reports memory to the OS.

There are also boot time options to get Linux to see memory that the BIOS fails to report. I forget the details, but I've seen them in other posts on this topic in LinuxQuestions. So far as I understand, those only work for memory the BIOS has remapped, but not reported. More often, any memory the BIOS doesn't report, it hasn't even remapped. I don't know if there is any work around within Linux if the BIOS hasn't remapped the memory.

Last edited by johnsfine; 07-12-2008 at 07:12 AM.
 
Old 07-14-2008, 04:23 AM   #4
a_patch
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Registered: Jun 2008
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Hi all,
thanks for quick reply.

Quote:
Originally Posted by watcher69b View Post
can your system BIOS recognise memory above 3gb? when the laptop starts up do you see it in the POST?
That was strange. Actually I check only BIOS info and there was 4096. I was pretty sure this is enough. But after yours post I check it and, what a surprise, there is only 3063.

johnsfine - as was expected, system see only 3GB.

Thank,s right now everything is in toshiba support hands.

One more think: in my manual is that this laptop support up to 4096MB RAM, on Toshiba website are two other manuals and in one of them is support only for 2048.

Last edited by a_patch; 07-14-2008 at 04:25 AM. Reason: additional info
 
  


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