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x86 extensions and their compatibility?
Hi all,
I have been seeing items in articles that have prompted several questions about the differences between AMD's x86 extensions and Intel's x86 extensions. Will AMD Opterons and Intel EM64T enabled chips run the EXACT same op code set? If there is a difference between the two then software suppliers will have three choices under which to release their products: common, amd variation and the intel variation. Is anyone familiar with this scenario? and what op codes each one runs? thanks, charles.... |
#2
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***** charles wrote:
Hi all, I have been seeing items in articles that have prompted several questions about the differences between AMD's x86 extensions and Intel's x86 extensions. Will AMD Opterons and Intel EM64T enabled chips run the EXACT same op code set? Yes, the opcodes are exactly the same. If there is a difference between the two then software suppliers will have three choices under which to release their products: common, amd variation and the intel variation. Most applications software will not need special versions at all -- they aren't affected by any of the minor differences. The only type of software that might be affected are operating systems. And operating systems kernels can usually deal with the differences by simply having a few inline "if ... then ..." conditions which take care of it on the spot. The differences exist not because of opcode differences but because of hardware implementation differences. For example, there is talk that certain Intel chipsets won't allow DMA access beyond the 32-bit boundary, even though the processor itself can address more than that, while AMD chipsets have no such restrictions. The OS would then have to detect what chipset it is running on, and allocate a DMA buffer appropriately. These implementation differences existed even on 32-bit x86, but they are getting fewer as time went on. Yousuf Khan |
#3
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"Yousuf Khan" wrote in message
... ***** charles wrote: Hi all, I have been seeing items in articles that have prompted several questions about the differences between AMD's x86 extensions and Intel's x86 extensions. Will AMD Opterons and Intel EM64T enabled chips run the EXACT same op code set? Yes, the opcodes are exactly the same. If there is a difference between the two then software suppliers will have three choices under which to release their products: common, amd variation and the intel variation. Most applications software will not need special versions at all -- they aren't affected by any of the minor differences. The only type of software that might be affected are operating systems. And operating systems kernels can usually deal with the differences by simply having a few inline "if ... then ..." conditions which take care of it on the spot. The differences exist not because of opcode differences but because of hardware implementation differences. For example, there is talk that certain Intel chipsets won't allow DMA access beyond the 32-bit boundary, even though the processor itself can address more than that, while AMD chipsets have no such restrictions. The OS would then have to detect what chipset it is running on, and allocate a DMA buffer appropriately. These implementation differences existed even on 32-bit x86, but they are getting fewer as time went on. Would an implementation/recompile with Gentoo be different between a dual opteron motherboard and a dual xeon em64t motherboard? charles..... |
#4
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***** charles wrote:
These implementation differences existed even on 32-bit x86, but they are getting fewer as time went on. Would an implementation/recompile with Gentoo be different between a dual opteron motherboard and a dual xeon em64t motherboard? Well, Gentoo is an extremely configurable Linux, the whole idea behind it is to customize it to the level of silliness. So yes, Gentoo could be made so customized that it won't work on any other x86 except the one it was meant for. They customize Gentoo to even remove hardware conditionals. Yousuf Khan |
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