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FreeBSD Boots on x86-64
craig2787 writes "FreeBSD developer Peter Wemm has successfully booted FreeBSD on a real AMD ClawHammer CPU, in both 64- and 32-bit modes. Original posting to the -current mailing list is here."
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According to reports I've read, the new Opteron actually outperforms the current Athlon clock-for-clock in 32-bit Legacy mode (32-bit OS running 32-bit code) because at base, the decode paths and functional unit pipelines are similar to the present generation processor. There are some additional tricks they have pulled to get some more speed, like a "smart" TLB that only flushes its cache of page table entries when truly necessary (not at every context switch).
In 64-bit Mode (where a 64-bit OS runs 64-bit code), average instruction length has increased because of the addition of a preface byte to every 64-bit instruction, but overall code size has DECREASED because 8 additional general purpose registers have been added (reducing compiler generated load/store code). This decrease in code size compensates for the larger average instruction length and enables performance to remain on-par with 32-bit.
However, I will feel much better about these claims once I have seen some true performance comparisons at an independent reviewer's site! :)
It was a joke, I changed the clock speed strings to 'pi'. This is a 10 month old pre-pre-pre-production A0-step silicon machine. I'm not allowed to talk about the speed of this particular machine. But I can say that I'm rather impressed given this particular machine's early production state. It does run very nicely in 32 bit mode. It is faster than my home desktop machine, and is faster than my work desktop (in single processor mode).
Also, note this is a Clawhammer cpu, not the Sledgehammer/Opteron that is coming up for release on April 23.