Alexander Puchmayr wrote:
Am Donnerstag, 6. Dezember 2018, 10:27:31 CET schrieb Dale:
Howdy,
I mentioned in other threads that I'm doing some upgrades to my system.
My first question is about a CPU upgrade. I currently have this for my
CPU, from cpuinfo:
AMD Phenom(tm) II X4 955 Processor
I've bought but not yet installed a FX-8350 CPU. I have this in my
make.conf file:
CFLAGS="-march=native -O2 -pipe"
Compiling the whole system with -march=native might lead to troubles,
especially when doing a CPU change. This option means that gcc is determining
the type of CPU automatically and adjusts the instruction set used to exactly
this CPU. Although, in your case, it is highly likely that your new CPU
understands all commands from the old, but I wouldn't bet on it. Its possible
that your existing software encounters problems like "illegal instruction" or
the like. Very bad if your compiler crashes after CPU replacement, then you
cannot emerge anything. I highly recommend using CFLAGS="-O2 -pipe" and
nothing more, the performance difference is, if measurable at all, negligible.
USE_CPU="fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt
pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nopl nonstop_tsc
extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic
cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt
nodeid_msr hw_pstate npt lbrv svm_lock nrip_save"
As someone else in this thread already mentioned, USE_CPU is not used. What
you're looking for is CPU_FLAGS_X86=..., which defines what cpu-specific options
will be enabled for packages supporting it and where it makes sense. See
package cpuid2cpuflags for details.
Regards
Alex
It seems the holiday shopping is slowing down delivery. My fan was
supposed to be here today but didn't arrive. Since I got time, I'll
change the CFLAGS for at least the @system stuff, that should get me
booted for sure. While the native setting makes things easier for
normal use, I can see the point of not using it when changing CPUs.
That is one reason for this thread. The CPUs are different and may
require some changes during the swap.
Is there a easy way to see what if any changes will be made? I did a
emerge -UDNa @system but it's not showing any change. Does it require a
emerge -e @system to force the change? Or is it not changing anything?
Thanks much. Better safe than sorry. ;-)
Dale
:-) :-)