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#46
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XP 32 bit Memory
J. P. Gilliver (John) wrote:
When I suggested a memory manager, I wasn't talking about going beyond the 4G limit, I was talking about accessing the RAM within the 4G but beyond where hardware sits on some machines, i. e. using non-contiguous memory. That is a hardware problem that you cannot solve with software. That is why the memory remapping function were invented. |
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#47
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XP 32 bit Memory
J. P. Gilliver (John) wrote:
When I suggested a memory manager, I wasn't talking about going beyond the 4G limit, I was talking about accessing the RAM within the 4G but beyond where hardware sits on some machines, i. e. using non-contiguous memory. That is a hardware problem that you cannot solve with software. That is why the memory remapping function were invented. |
#48
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XP 32 bit Memory
dennis wrote:
John John - MVP wrote: I know that a certain RAM disk can apparently make use of the memory above the 4GB barrier, I guess this is what you mean by "device space". With device space I mean this: http://msdn.microsoft.com/en-us/library/ms801998.aspx Thanks for the link. In one of his blogs Mark Russinovich said that "...problematic client driver ecosystem led to the decision for client SKUs to ignore physical memory that resides above 4GB, even though they can theoretically address it." My understanding about this is that while (some of) the server versions can do this the whole point of limiting memory access below 4GB on clients with PAE was to specifically prevent drivers from playing in the upper memory arena. So now I'm not sure what to think... http://blogs.technet.com/markrussino...1/3092070.aspx Mark's Blog : Pushing the Limits of Windows: Physical Memory John |
#49
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XP 32 bit Memory
dennis wrote:
John John - MVP wrote: I know that a certain RAM disk can apparently make use of the memory above the 4GB barrier, I guess this is what you mean by "device space". With device space I mean this: http://msdn.microsoft.com/en-us/library/ms801998.aspx Thanks for the link. In one of his blogs Mark Russinovich said that "...problematic client driver ecosystem led to the decision for client SKUs to ignore physical memory that resides above 4GB, even though they can theoretically address it." My understanding about this is that while (some of) the server versions can do this the whole point of limiting memory access below 4GB on clients with PAE was to specifically prevent drivers from playing in the upper memory arena. So now I'm not sure what to think... http://blogs.technet.com/markrussino...1/3092070.aspx Mark's Blog : Pushing the Limits of Windows: Physical Memory John |
#50
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XP 32 bit Memory
In message , dennis
writes: J. P. Gilliver (John) wrote: When I suggested a memory manager, I wasn't talking about going beyond the 4G limit, I was talking about accessing the RAM within the 4G but beyond where hardware sits on some machines, i. e. using non-contiguous memory. That is a hardware problem that you cannot solve with software. That is why the memory remapping function were invented. They seemed to solve it OK in the days of DOS and the (I think it was) 640K barrier, with LOADHI (IIRR) and so on; ISTR prog.s and drivers had to be loadhigh aware, or something like that. It's all a Long Time Ago .... -- J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf ** http://www.soft255.demon.co.uk/G6JPG-PC/JPGminPC.htm for ludicrously outdated thoughts on PCs. ** Reality and talent shows lack honesty. They manipulate the viewer with mawkish stories. Contestants turn tragedies into qualifications. - Sean Lock, in Radio Times, 20-26 June 2009 |
#51
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XP 32 bit Memory
In message , dennis
writes: J. P. Gilliver (John) wrote: When I suggested a memory manager, I wasn't talking about going beyond the 4G limit, I was talking about accessing the RAM within the 4G but beyond where hardware sits on some machines, i. e. using non-contiguous memory. That is a hardware problem that you cannot solve with software. That is why the memory remapping function were invented. They seemed to solve it OK in the days of DOS and the (I think it was) 640K barrier, with LOADHI (IIRR) and so on; ISTR prog.s and drivers had to be loadhigh aware, or something like that. It's all a Long Time Ago .... -- J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf ** http://www.soft255.demon.co.uk/G6JPG-PC/JPGminPC.htm for ludicrously outdated thoughts on PCs. ** Reality and talent shows lack honesty. They manipulate the viewer with mawkish stories. Contestants turn tragedies into qualifications. - Sean Lock, in Radio Times, 20-26 June 2009 |
#52
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XP 32 bit Memory
Thanks for the link. In one of his blogs Mark Russinovich said that "...problematic client driver ecosystem led to the decision for client SKUs to ignore physical memory that resides above 4GB, even though they can theoretically address it." My understanding about this is that while (some of) the server versions can do this the whole point of limiting memory access below 4GB on clients with PAE was to specifically prevent drivers from playing in the upper memory arena. So now I'm not sure what to think... http://blogs.technet.com/markrussino...1/3092070.aspx Mark's Blog : Pushing the Limits of Windows: Physical Memory You also don't use this function to allocate memory. All the memory allocation functions that the drivers (normally) use will always allocate memory below 4G in 32bit XP. |
#53
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XP 32 bit Memory
Thanks for the link. In one of his blogs Mark Russinovich said that "...problematic client driver ecosystem led to the decision for client SKUs to ignore physical memory that resides above 4GB, even though they can theoretically address it." My understanding about this is that while (some of) the server versions can do this the whole point of limiting memory access below 4GB on clients with PAE was to specifically prevent drivers from playing in the upper memory arena. So now I'm not sure what to think... http://blogs.technet.com/markrussino...1/3092070.aspx Mark's Blog : Pushing the Limits of Windows: Physical Memory You also don't use this function to allocate memory. All the memory allocation functions that the drivers (normally) use will always allocate memory below 4G in 32bit XP. |
#54
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XP 32 bit Memory
J. P. Gilliver (John) wrote:
They seemed to solve it OK in the days of DOS and the (I think it was) 640K barrier, with LOADHI (IIRR) and so on; ISTR prog.s and drivers had to be loadhigh aware, or something like that. It's all a Long Time Ago ... The problem with not all 4GB being usable is because MMIO is overlapping the address space where your RAM lives. All memory addresses in that region are redirected to the IO-system. So you cannot get to that RAM. Memory remapping solves that by remapping ram in that region up above 4G, so you can address it there instead (which 32bit XP doesn't do willingly). |
#55
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XP 32 bit Memory
J. P. Gilliver (John) wrote:
They seemed to solve it OK in the days of DOS and the (I think it was) 640K barrier, with LOADHI (IIRR) and so on; ISTR prog.s and drivers had to be loadhigh aware, or something like that. It's all a Long Time Ago ... The problem with not all 4GB being usable is because MMIO is overlapping the address space where your RAM lives. All memory addresses in that region are redirected to the IO-system. So you cannot get to that RAM. Memory remapping solves that by remapping ram in that region up above 4G, so you can address it there instead (which 32bit XP doesn't do willingly). |
#56
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XP 32 bit Memory
There is another teensy weensy problem.
Microsoft using various means, does not allow legal modification of windows core by "outsiders" to allow relocation to "unused" memory. Since hardware, with a proper memory manager, in hardware and software, usually can do such things, the problem ends up going back to Microsoft's code. After all, memory mapping is a very old technique, going back to the minicomputers, if not farther back in history. Some of the minicomputers had an rough equivalent to Windows swap file, in that if enough memory was installed, resided in memory rather than only on disk. At one point, some of HP's systems swapped out almost anything that was not currently in use. The ops system maintained a table that was used to find everything. (1970's) long before Apple, etc. One of the major problems is the compatibility issue with older P/C hardware and "standards" that are the result of "IBM compatibility", based on a crippled hardware design intended to prevent competition with mainframe capabilities and save hardware costs. The older schemes also were usually intended for use with multiusers, be the "users" a physical person, or a process. "dennis" wrote in message ... J. P. Gilliver (John) wrote: They seemed to solve it OK in the days of DOS and the (I think it was) 640K barrier, with LOADHI (IIRR) and so on; ISTR prog.s and drivers had to be loadhigh aware, or something like that. It's all a Long Time Ago ... The problem with not all 4GB being usable is because MMIO is overlapping the address space where your RAM lives. All memory addresses in that region are redirected to the IO-system. So you cannot get to that RAM. Memory remapping solves that by remapping ram in that region up above 4G, so you can address it there instead (which 32bit XP doesn't do willingly). |
#57
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XP 32 bit Memory
There is another teensy weensy problem. Microsoft using various means, does not allow legal modification of windows core by "outsiders" to allow relocation to "unused" memory. Since hardware, with a proper memory manager, in hardware and software, usually can do such things, the problem ends up going back to Microsoft's code. After all, memory mapping is a very old technique, going back to the minicomputers, if not farther back in history. Some of the minicomputers had an rough equivalent to Windows swap file, in that if enough memory was installed, resided in memory rather than only on disk. At one point, some of HP's systems swapped out almost anything that was not currently in use. The ops system maintained a table that was used to find everything. (1970's) long before Apple, etc. One of the major problems is the compatibility issue with older P/C hardware and "standards" that are the result of "IBM compatibility", based on a crippled hardware design intended to prevent competition with mainframe capabilities and save hardware costs. The older schemes also were usually intended for use with multiusers, be the "users" a physical person, or a process. "dennis" wrote in message ... J. P. Gilliver (John) wrote: They seemed to solve it OK in the days of DOS and the (I think it was) 640K barrier, with LOADHI (IIRR) and so on; ISTR prog.s and drivers had to be loadhigh aware, or something like that. It's all a Long Time Ago ... The problem with not all 4GB being usable is because MMIO is overlapping the address space where your RAM lives. All memory addresses in that region are redirected to the IO-system. So you cannot get to that RAM. Memory remapping solves that by remapping ram in that region up above 4G, so you can address it there instead (which 32bit XP doesn't do willingly). |
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