Message-ID: From: yjtseng To: "Salvador Eduardo Tropea (SET)" , dj AT delorie DOT com, djgpp AT delorie DOT com Cc: yjtseng AT micron DOT com Subject: cwsdpr0.exe 4/14/99 Date: Wed, 14 Apr 1999 15:57:46 -0600 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2448.0) Content-Type: text/plain; charset="iso-8859-1" Reply-To: djgpp AT delorie DOT com All right, Now, fact: CR0=0x80000019 which means paging is on. If I maps physical address 0xfb000000 to linear address using __dpmi_physical_address_mapping(&mi) as shown in FAQ 18.7, the returned linear address is 0xfb00000000 which the same as physical address 0xfb000000. How can this be? It does not make sense, right? Unless the paging mechanism is off, which is not true, as evidenced by CR0=0x80000019. Since paging is used, shouldn't the linear address be different from the physical address after Int 31H, function 0800H? Any idea? Thanks. Jay -----Original Message----- From: Salvador Eduardo Tropea (SET) [SMTP:salvador AT inti DOT gov DOT ar] Sent: April 13, 1999 8:40 AM To: yjtseng Subject: Re: FW: cwsdpr0.exe 4/13/99 Hi Jay: > What will happen if virtual memory is disabled (as is in cwsdpr0.exe), > paging is enabled (as shown in CR0 I read), and pages need to be swapped > out? All the pages are marked as non-swap. > Is this a legitimate scenario? Of course! as I told you DOS's EMM386 uses it to emulate EMS. The code enters in PM and creates a virtual machine for the RM programs. That's why a lot of PM programs for DOS can't run when EMM386 is loaded. Remapping pages EMM386 can emulate EMS (hardware paged memory used in 286 machines). > Or, can you do paging without swapping pages to/from disk storage? Paging mechanism is not only for VM. You can remap memory and protect pages, for it you don't need swap at all. SET ------------------------------------ 0 -------------------------------- Visit my home page: http://welcome.to/SetSoft or http://www.geocities.com/SiliconValley/Vista/6552/ Salvador Eduardo Tropea (SET). (Electronics Engineer) Alternative e-mail: set-soft AT usa DOT net set AT computer DOT org ICQ: 2951574 Address: Curapaligue 2124, Caseros, 3 de Febrero Buenos Aires, (1678), ARGENTINA TE: +(5411) 4759 0013