Showing results for Other - The Old New Thing

Aug 12, 2004
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Myth: The /3GB switch expands the user-mode address space of all programs

Raymond Chen
Raymond Chen

Only programs marked as /LARGEADDRESSAWARE are affected. For compatibility reasons, only programs that explicitly indicate that they are prepared to handle a virtual address space larger than 2GB will get the larger virtual address space. Unmarked programs get the normal 2GB virtual address space, and the address space between 2GB and 3GB goes u...

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Aug 11, 2004
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Myth: You need /3GB if you have more than 2GB of physical memory

Raymond Chen
Raymond Chen

Physical memory is not virtual address space. In my opinion, this is another non sequitur. I'm not sure what logical process led to this myth. It can't be a misapprehension of a 1-1 mapping between physical memory and virtual memory, because that mapping is blatantly not one-to-one. You typically have far more virtual memory than physical memory...

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Aug 10, 2004
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Myth: Without /3GB a single program can’t allocate more than 2GB of virtual memory

Raymond Chen
Raymond Chen

Virtual memory is not virtual address space (part 2). This myth is being perpetuated even as I write this series of articles. The user-mode virtual address space is normally 2GB, but that doesn't limit you to 2GB of virtual memory. You can allocate memory without it being mapped into your virtual address space. (Those who grew up with Expanded Me...

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Aug 9, 2004
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Myth: Without /3GB the total amount of memory that can be allocated across all programs is 2GB

Raymond Chen
Raymond Chen

Virtual memory is not virtual address space (part 1). I don't know where this myth comes from; it's a non sequitur. Virtual address space describes how addresses are resolved, but since each process has its own virtual address space, the amount consumed by one program has no effect on that consumed by another program. Say you have ...

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Aug 6, 2004
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Kernel address space consequences of the /3GB switch

Raymond Chen
Raymond Chen

One of the adverse consequences of the /3GB switch is that it forces the kernel to operate inside a much smaller space. One of the biggest casualties of the limited address space is the video driver. To manage the memory on the video card, the driver needs to be able to address it, and the apertures required are typically quite large. When...

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Aug 5, 2004
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The oft-misunderstood /3GB switch

Raymond Chen
Raymond Chen

It's simple to explain what it does, but people often misunderstand. The /3GB switch changes the way the 4GB virtual address space is split up. Instead of splitting it as 2GB of user mode virtual address space and 2GB of kernel mode virtual address space, the split is 3GB of user mode virtual address space and 1GB of kernel mode virtual addr...

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Jul 22, 2004
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Why can't you trap TerminateProcess?

Raymond Chen
Raymond Chen

If a user fires up Task Manager and clicks "End Task" on your program, Windows first tries to shut down your program nicely, by sending WM_CLOSE messages to GUI programs and CTRL_CLOSE_EVENT events to console programs. But you don't get a chance to intercept TerminateProcess. Why not? TerminateProcess is the low-level process killing function. It...

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Jul 22, 2004
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Why can’t you trap TerminateProcess?

Raymond Chen
Raymond Chen

If a user fires up Task Manager and clicks "End Task" on your program, Windows first tries to shut down your program nicely, by sending WM_CLOSE messages to GUI programs and CTRL_CLOSE_EVENT events to console programs. But you don't get a chance to intercept TerminateProcess. Why not? TerminateProcess is the low-level process killing function. It...

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Jul 15, 2004
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Why "Under Construction" should be made illegal on the web

Raymond Chen
Raymond Chen

The site www.emr.fr has been "under construction" for over eight years. I noticed it in June 1996 and check back on it periodically. Still Under Construction. Another site that I noticed as "Under Construction" in June 1996 is www.leary.com. And as of this writing, it is still under construction.

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Jul 15, 2004
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Why “Under Construction” should be made illegal on the web

Raymond Chen
Raymond Chen

The site www.emr.fr has been "under construction" for over eight years. I noticed it in June 1996 and check back on it periodically. Still Under Construction. Another site that I noticed as "Under Construction" in June 1996 is www.leary.com. And as of this writing, it is still under construction.

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