> -----Original Message----- > From: Ben Scott [mailto:[EMAIL PROTECTED] > > > All 32bit OS's have this limitation, even Windows Server. > > No, they do not.
I qualified my statement by mentioning PAE. Granted, 10 years of time is what it is and I should have worded that statement better. > This isn't just about PAE. In some cases, XP apparently refuses to > recognize RAM located below the 4 GiB mark on the physical address > bus, but which is not used by other hardware. Exact circumstances and > explanations are unclear and/or poorly documented. Well, what I'm talking about is about PAE. That is if we're talking about 4GB of memory, 4GB of physical address space, and Windows XP/2K3. I don't think it's poorly documented or worded necessarily. XP is built with the restriction by design as plainly mentioned on Microsoft's PAE webpage: "Total physical address space is limited to 4 GB on these versions of Windows [1]" > You are ignoring the difference between virtual address space and > physical address space. No, I'm just not talking about virtual address space, see above. > Hardware which properly supports the full PCI spec, and with > software which properly handles physical addresses above 4 GiB, can > support physical addresses above the 4 GiB mark. Those physical > addresses will be mapped into the 4 GiB virtual address space. What's the point? If XP (and some 2K3/8's) can't address above that barrier then what good would it do to run them in a system that only supports up to 4GB in the first place? It puts you right back at the beginning of the conversation. XP (and some 2K3/8's) will ignore the boot time mapping of address space and remap devices below the 4GB barrier if they start out above [2]. Something notable from HP's website: "Expansion cards and embedded devices such as PCI, PCI-X, and PCI-Express devices require memory that is mapped below 4 GB. [3]" So again, you're right about "some hardware", but it's only really relevant to OS's that are not bound by the restriction to physical address space below 4GB. I dunno, I don't think were worlds apart here, it's just a complex subject. I was just trying to avoid the complexity and keep it simple. -- Mike Gill [1] http://www.microsoft.com/whdc/system/platform/server/PAE/PAEdrv.mspx [2] http://www.microsoft.com/whdc/archive/PCI-rsc.mspx [3] http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c0088 3105&dimid=1438676018&dicid=alr_mar07&jumpid=em_alerts/us/mar07/all/xbu/emai lsubid/mrm/mcc/loc/rbu_category/alerts ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~
