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Re: Changing the default 32-bit x86 arch for Fedora 12 (#2)



"Richard W.M. Jones" <rjones redhat com> writes:

>> - Build all packages for i686 (this requires cmov)
>
> This cuts out AMD Geode ...

No, though it cuts out VIA C3 (used mostly(?) on EPIA (mini-ITX)
boards). I have one but it had never run Fedora (only PXE ramdisk-based
small LFS).

Hmm... Just checked and it seems they still list EPIA-M and others as
"available". I'm not sure what to think about that:

- The CPU in question is C3 Eden / Samuel 2 / Ezra (not sure about
  the difference but C3-2(?) aka Nehemiah seems to be CMOV-capable).

- I think the clock range is 400 - 1000 MHz, though I've only seen 600+
  MHz versions.

- it seems they've started selling mini-ITX EPIAs in 2002

- low-power fanless boards, the old EPIA-M was capable of hardware
  decoding MPEG2 and I'm told newer boards can do MPEG4 in hardware as
  well - they are/were popular as DVD/digital TV/DVR boxes.

- Eden CPU datasheet dated Jan 18, 2006 states that "CMOV and FCMOV
  instructions available" and "Notes On CPUID Feature Flags: The
  CMPXCHG8B instruction is provided and always enabled, however, it can
  be disabled in the corresponding CPUID function bit 8 to avoid a bug
  in an early version of Windows NT. However, this default can be
  changed via bit 1 in the FCR MSR."

- Maybe Samuel 2 and Ezra are non-cmov and Eden is cmov-able?

I don't say if those CPUs have to be supported by Fedora, I'm just
posting this for completeness.
-- 
Krzysztof Halasa


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