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mxfm
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PostPosted: Mon Aug 08, 2016 5:32 pm    Post subject: Installation on external bootable USB drive Reply with quote

Hi!

I am several years of linux experience (suse, fedora, debian, arch) and now look at gentoo. I made research on gentoo and have several questions.

Firstly I use external bootable USB disk to work with my laptop, as well as with other computers (often I had to) - this means that when I plug the drive into another computer, I expect to be able to boot kernel with all necessary drivers and modules loaded. In the past I always used binary distribution with kernel targeted at wide range of hardware - and indeed, it worked out of the box in almost all cases. In case of gentoo, it serves best when targeted for a specific computer. As far as I understand, this means that 1) such advantage of gentoo as targeting at specific computer is lost 2) I have to make such config, with which kernel will likely work out of the box on random modern computer.

Secondly, after reading materials my impression is that gentoo often requires resolving errors after frequent updates (because something is not compiling, is not linking, etc). It is also written that gentoo requires constant manitaining efforts. Is this true?

Thirdly, I prefer GNOME. Is systemd necessary for it?

Lastly, if I use GNOME and firefox, how long does it take to compile? How often they are updated which requires recompilation?

Thanks in advance.

P. S. Actually, I am mostly concerned with first question #1 - when I tried to install gentoo at first time, kernel panicked early on boot because of lacking scsi usb drivers: i tried to include all related kernel modules, but the system was still unbootable.
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NeddySeagoon
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PostPosted: Mon Aug 08, 2016 7:08 pm    Post subject: Reply with quote

mxfm,

Welcome to Gentoo.

The trick to putting the root filesystem onto a USB drive is to know that the kernel normally mounts root before the USB subsystem is started.
That's a problem when root is on USB. The fix is to pass the kernel either rootwait, or rootdelay=<sec>.
rootwait tell the kernel hot to mount root until its available. It will wait forever.
rootdelay=<secs> tells the kerne to wait <secs> before mounting root.

Unfortunately, when given on the kernel command line when an initrd is in use, the delay is applied to the initrd root, not the hdd root.
That needs the delay to be included inside the initrd.

1) You would need to find a common set of optimisations that would work on all the systems you wanted to run the single install on.
It can be done. Look at the Gentoo liveDVD as a working example.
Its also possible to have a common core set of packages and build a smal numer of packages for a particular target, where performance matters.
For example, multimedia applications, which take advantage of the various multimedia instruction set extensions.
A few packages do run time CPU detection too, so that they need not be a problem.

The response to 1 is not kernel specific. It also applies to other packages.

2) Errors on update are largely down to the user. There are two clearly defined branches is Gentoo. Stable and testing. Testing, is well testing. If you use that expect a few bupms in the road. Stable is straight forward. Most problems arise when users try to mix branches. The rule is that stable may only depend on other stable packages. Testing can depend on other testing and/or other stable packages. This gives rise to the situation where you need two different versions of the same library installed at the same time. You have to make the decisions then.

3) systemd is not required for GNOME on Gentoo. There is a sticky thread about it on these forums.

Build times vary. On a AMD Phenom(tm) II X6 1090T Processor.
Code:
$ sudo genlop -t firefox
Password:
 * www-client/firefox

     Sat Mar 12 12:52:07 2016 >>> www-client/firefox-45.0
       merge time: 21 minutes and 17 seconds.

     Sat Mar 26 13:15:11 2016 >>> www-client/firefox-45.0.1
       merge time: 18 minutes and 51 seconds.

     Sun Jul 31 16:26:45 2016 >>> www-client/firefox-47.0.1
       merge time: 18 minutes and 3 seconds.


On a Raspberry Pi3
Code:
genlop -t firefox
 * www-client/firefox

     Wed Jun 29 03:13:06 2016 >>> www-client/firefox-47.0
       merge time: 9 hours, 21 minutes and 5 seconds.

     Mon Jul 25 12:32:37 2016 >>> www-client/firefox-47.0.1
       merge time: 12 hours, 40 minutes and 20 seconds.


I update monthly as a matter of routine. Gentoo is a rolling release, you need to roll with it or risk problems with routine updates.
In practice, these are solved by doing the updates you thought you had skipped.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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mxfm
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PostPosted: Tue Aug 09, 2016 7:22 am    Post subject: Reply with quote

NeddySeagoon wrote:
mxfm,


Thanks. Answer to q1 is close to what I expected. I am glad to hear that compilation is quite fast and that updates do not always require manual fixes.
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