Re: Linux-5.2.8 configuration: Intel Atom x5-Z8330 and CONFIG_MATOM

Hans Malissa <[email protected]> Sun, 09 Feb 2020 23:52:58 -0000
Newsgroups gmane.linux.lfs.general
Message-ID <[email protected]>
On February 9, 2020 at 2:06 PM, Ken Moffat <[email protected]> wrote:
On Sun, Feb 09, 2020 at 07:32:49PM -0000, Hans Malissa wrote:
This is not a support request; I'm mainly asking out of curiosity (that's why I'm posting this in lfs-chat).
My CPU is an Intel Atom x5-Z8330 (06-4c-04) (https://www.intel.com/content/www/us/en/products/boards-kits/compute-stick/stk1a32sc.html), and during the configuration of Linux-5.2.8 there is an item in 'Processor type and features' under 'Processor family' that says 'Intel Atom' (CONFIG_MATOM). The description says: 'Select this for the Intel Atom platform. Intel Atom CPUs have an in-order pipelining architecture and thus can benefit from accordingly optimized code. Use a recent GCC with specific Atom support in order to fully benefit from selecting this option.'. I'm not sure what that means. Does the GCC that's built during LFS/BLFS have such a 'specific Atom support' or what would it take to get that? LFS runs fine with the 'Generic-x86-64' option; I'm just wondering if I can get more out of this CPU.
Thanks a lot!

A quick google for 'gcc with support for intel atom' suggests it was
added in gcc-4.5. A link to

https://software.intel.com/en-us/blogs/2013/05/28/why-should-i-update-gcc-x86-compiler-or-gcc-compiler-performance-on-intel-atom-from

Shows that late gcc-4.4 (4.4.6) had some additions and by 4.8.1 it
seems to have all been in place.

Therefore I conclude that the configure help text is somewhat old.
I'm not sure of the current minimum gcc version required for
building a kernel on x86, perhaps lesser gcc versions are still
usable in general, but any LFS version from LFS-7.4 onwards
(September 2013) should be good enough for an Intel Atom.

ĸen
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This makes sense, thanks a lot. I will recompile the kernel with CONFIG_MATOM and leave gcc as it is.

Hans 

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