Re: [gentoo-user] CPU upgrade and LVM questions.

[Dale <rdalek1967@gmail.com>]

Jack wrote:
> On 2018.12.06 15:58, Dale wrote:
> [snip...]
>> My concern is this tho.  I have my old CPU still installed and
>> everything is compiled based on that.  So, I'm stable with the old
>> CPU.  However, when I shutdown, take out the old CPU and install the
>> new one, I'm concerned it may not boot at all because of the change
>> or may boot but be very unstable.  I recall years ago being able to
>> set up the flags in such a way that it can run on virtually any CPU
>> but it's been a long time ago and I don't know if it is needed or
>> not.  My hope was, someone did a very similar upgrade and can say for
>> sure if it works or if I need to do things before changing the CPUs
>> to make sure I can boot and be stable.  If I can just get a stable
>> console, I can do a emerge -e world and get the OS inline with the
>> CPU.  I'm just concerned whether I will have that or not. 
>>
> [snip...]
>>
>> I just don't want to swap CPUs only to find out I've got to swap back
>> because my system won't boot at all. Heck, it may even fail to load
>> the kernel itself for all I know. 
> I once made the mistake of getting a whole new (used...) PC and just
> moved the HDD from the old one to the new, without thinking about any
> of this.  Of course it wouldn't boot at all, because I was switching
> from an AMD to an Intel CPU and had set all flags accordingly in the
> old box.  In your case, as long as you include any flags necessary for
> the new CPU, and remove any flags for features the new CPU does not
> have, you should be good.  (I know that sounds simple, but does ignore
> how you find that info.)  Given your two CPUs are relatively close
> (unless I misread something) there should be little if anything
> critical to change.
>
> However, if you have a live DVD, (or on USB stick) that will always
> boot, and you can then do a chroot and reset flags and start
> recompiling whatever might fail.   I actually think the kernel IS the
> likely failure if any, but once that boots, you should be good to
> recompile whatever fails.  (Yes, toolchain stuff might be an issue,
> but again, just boot back to the live DVD.)  You may need to reboot a
> few times, but you won't need to swap the old CPU back in.
>
> Jack
>

I've tried that too.  Heck, sometimes that doesn't work even with
windoze.   My concerns are sort of along those lines tho.  I don't have
and can't find the current flags for the new CPU so I don't know what to
do flag wise.  I'm not sure that there is even a common setting but
suspect there is.  If I can get the kernel to boot and login at a
console, even with no X, I can rebuild from there, provided everything
works toolchain wise. 

I guess this is a good time to make sure my sysrescue and other tools
work.  That slipped my mind completely.  Thanks for the reminder.  Hmmm,
I need to check on the current mount and chroot process for this too. 

Thanks.

Dale

:-)  :-)