Red Hat Bugzilla – Bug 208843
4gb RAM shown as 3GB on nx6325
Last modified: 2007-11-30 17:11:44 EST
From Bugzilla Helper: User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) Description of problem: Fedora onlys show 3GB of RAM even when 4GB is in the machine. It is an HP NX6325 dual core 64 bit AMD laptop. The BIOS shows 4GB RAM after entering F10 and will do a full memory test on 4GB However I do get this message after inserting the memory: The following configuration options were automatically updated: Total memory installed:3014656 Windows XP shows 3GB of RAM from task manager but 4GB RAM from msinfo32 How can we get Fedora to use the full 4GB RAM ? I have tried adding the parameter mem=4096M to the grub line but it does not help. Version-Release number of selected component (if applicable): 2.6.17-1.2187_FC5 How reproducible: Always Steps to Reproduce: 1. insert 2*2GB SODIMMS into the HP nx6325 laptop 2. boot into fedora 3. enter the free command, or use Gnome System Monitor, or cat /more/meminfo Actual Results: total shown is 2934984 Expected Results: 3983560 Additional info: Have reproduced on: FC5 2.6.17-1.2187_FC5 rawhide rescue disk 2.6.17-1.2630 RHEL 5 beta1 2.6.17-1.2519.4.21.el5
Have you tried to turn of "PCI remapping" in the BIOS? It could be called "IOMMU 4GB remap" or something like that - each BIOS vendor calls it differently.
There are no such BIOS options. See the menus in the doc http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00715299/c00715299.pdf
A new kernel update has been released (Version: 2.6.18-1.2200.fc5) based upon a new upstream kernel release. Please retest against this new kernel, as a large number of patches go into each upstream release, possibly including changes that may address this problem. This bug has been placed in NEEDINFO state. Due to the large volume of inactive bugs in bugzilla, if this bug is still in this state in two weeks time, it will be closed. Should this bug still be relevant after this period, the reporter can reopen the bug at any time. Any other users on the Cc: list of this bug can request that the bug be reopened by adding a comment to the bug. In the last few updates, some users upgrading from FC4->FC5 have reported that installing a kernel update has left their systems unbootable. If you have been affected by this problem please check you only have one version of device-mapper & lvm2 installed. See bug 207474 for further details. If this bug is a problem preventing you from installing the release this version is filed against, please see bug 169613. If this bug has been fixed, but you are now experiencing a different problem, please file a separate bug for the new problem. Thank you.
Peter, The problem is not with Fedora, nor Windows, nor any Operating System. It is the BIOS using the 3GB-4GB memory address as an IOMMU hole. Most of the BIOSes I have seen have an option to change the size of the IOMMU, disable it, or "remaping" requests (which is what your BIOS is doing).Look in the BIOS for GART options, perhaps you can change some of those settings. I am closing this BZ as NOTABUG since it is not a Fedora bug but a the BIOS not having an proper option.
Konrad Thanks for the succint answer. I shall your comments to HP and request that they put these options in the BIOS. The only BIOS setting that I can find that is remotely related is BIOS DMA Data Transfers Allows you to control how BIOS disk I/O requests are serviced. When “Enable” is selected, the BIOS will service ATA disk read and write requests with DMA data transfers. When “Disable” is selected, the BIOS will service ATA disk read and write requests with PIO data transfers. Would this help ? I am waiting for some faulty memory to be replaced so I can't test at presetn.
one more question would the kernel parameter pci=nommconf make any difference ?
BIOS DMA transfers - No. This is just a performance related option regarding how fast your disk I/O occurs. nommconf - no, this is to do with memory mapped PCI configuration space, nothing to do with the memory hole.