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ShanaXXII
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PostPosted: Mon Aug 04, 2014 10:42 pm    Post subject: Switching from Genkernel help Reply with quote

So today, I decided to switch to the manual configuration. I referenced to the installation handbook -> https://www.gentoo.org/doc/en/handbook/handbook-amd64.xml?full=1
I went into /usr/src/linux
started up the menuconfig with # make menuconfig
Idk if this is suppose to happen or not, but it read the configuration I had for genkernel. I checked multiple times to make sure.
So I exited the menuconfig, did # make && make modules_install
Then a # make install
I then updated my bootloader -> # grub2-mkconfig -o /boot/grub/grub.cfg
It found my Genkernel and its initramfs
Then my manual kernel and the initramfs from genkernel.
Then my windows 7 on a seperate partition

I rebooted and booted into the manual kernel no problem. But I didn't really want the initramfs with it.
So I went into the grub2 bootmenu and deleted the part to tell it to load the initramfs for the manually configured kernel.
Rebooted and tried to boot into it, and it failed to boot and stopped with an error. :\
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The Doctor
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PostPosted: Mon Aug 04, 2014 10:49 pm    Post subject: Reply with quote

See http://kernel-seeds.grytpype-thynne.org/working.html for advice on the proper way to configure a kernel. Unfortunately, the seeds are out of date, but the default config works just fine as a base. Don't forget to run make clean before rebuilding the kernel.

EDIT: Yes, Jaglover's suggestion is better. make clean only cleans up the files leftover from the build while make mrproper will clear the old .config as well.
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Last edited by The Doctor on Tue Aug 05, 2014 12:23 am; edited 1 time in total
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PostPosted: Mon Aug 04, 2014 11:00 pm    Post subject: Reply with quote

To clean up your kernel sources you should run make mrproper.
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ShanaXXII
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PostPosted: Tue Aug 05, 2014 1:06 am    Post subject: Reply with quote

Jaglover wrote:
To clean up your kernel sources you should run make mrproper.

I think it's already done that. Everytime I # genkernel --menuconfig all it always says running old config, running mrproper
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PostPosted: Tue Aug 05, 2014 1:20 am    Post subject: Reply with quote

When you run make menuconfig it will not run make mrproper for you.
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PostPosted: Tue Aug 05, 2014 12:00 pm    Post subject: Reply with quote

Jaglover wrote:
When you run make menuconfig it will not run make mrproper for you.

I ran mrproper, then # make menuconfig. # make && make modules_install. Then # make install
# grub2-mkconfig -o /boot/grub/grub.cfg
it gave me an error saying there is no file or directory.
I compiled genkernel again.
did # grub2-mkconfig -o /boot/grub/grub.cfg
it found Genkernel and its initramfs
it found vmlinuz and genkernel's initramfs.
it found windows 7 on a seperate partition.
I rebooted, went into grub2menu and deleted the part that told it to boot the initramfs when booting from vmlinuz.
I booted into it and it gave me an error:
I cant rememeber all of it, but it was something like this:
Code:
[Call Trace]
[ffffffff0x8049] .......
[ffffffff......]........
[fffffff.......]........
[ffffffff......]........
[ffffffff......]........
[fffffff.......]........
[ffffffff......]........
...
[end trace]
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wraeth
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PostPosted: Tue Aug 05, 2014 12:20 pm    Post subject: Reply with quote

ShanaXXII wrote:
I rebooted, went into grub2menu and deleted the part that told it to boot the initramfs when booting from vmlinuz.
I booted into it and it gave me an error:

This is because one or more of the drivers your kernel needs in order to boot is built as a module. This is a problem because the modules are stored on your root filesystem and, if your kernel lacks the necessary drivers for loading and mounting your root filesystem, it cannot boot. The reason it works with the initramfs is because that is one of the primary purposes of an initramfs - to provide modules for the kernel to be able to enumerate and load your root filesystem.

If you want to be able to boot your manual kernel without an initramfs, then you need to return to menuconfig and ensure that the drivers for your motherboard and filesystem are built-in to the kernel (<*>) and not built as modules (<M>).

Also, as a tip: when building the kernel, you can also use the -jX option the same as MAKEOPTS in your make.conf:
Code:
linux # make -j7 && make modules_install && make install

Edit:
It should be noted as well that one of the other purposes of an initramfs is to provide any userspace utilities needed for booting, such as cryptsetup for encrypted drives or lvm for lvm-based filesystems. If you use something like that, then you may not be able to boot without an initramfs.
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ShanaXXII
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PostPosted: Tue Aug 05, 2014 4:44 pm    Post subject: Reply with quote

wraeth wrote:
This is because one or more of the drivers your kernel needs in order to boot is built as a module. This is a problem because the modules are stored on your root filesystem and, if your kernel lacks the necessary drivers for loading and mounting your root filesystem, it cannot boot. The reason it works with the initramfs is because that is one of the primary purposes of an initramfs - to provide modules for the kernel to be able to enumerate and load your root filesystem.

I followed the tutorial here to build my kernel as mine is the same model. -> http://gentoo-en.vfose.ru/wiki/Dell_Inspiron_1564
The site isn't working right now for some reason :/ for me at least.
I also did a few changes here and there because mine is an i5 instead of an i3, and Intel HD graphics instead of ATI graphics.
But it still doesn't work.
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PostPosted: Tue Aug 05, 2014 5:56 pm    Post subject: Reply with quote

ShanaXXII,

Somewhere on the screen should be a message about a Kernel Panic

It might end it the text unknown-block(x,y) where x and y are numbers.
If you see that, tell us x and y. If not, the complete English text panic message will be useful.

Avoid make mrproper unless you really need it. It removes your .config file.
make clean should be sufficient. That leaves your .config alone.
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Arthanis
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PostPosted: Tue Aug 05, 2014 7:20 pm    Post subject: Reply with quote

As someone already said, probably you are missing drivers needed to read your root filesystem (i.e chipset, sata controller, etc).

I have always used manual configuration to keep my kernel clean, and what have helped me a lot is to boot any live CD (I recommend system rescue CD, but you can boot gentoo live as well) and run on prompt:

Code:
lspci -k


which will not only show you your current hardware, but also will show you the kernel module in use. Then you can take notes and search for their symbols in menuconfig, enable them (for sata and disk controllers built-in, not as modules), install your kernel, build modules and reboot.
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ShanaXXII
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PostPosted: Tue Aug 05, 2014 11:57 pm    Post subject: Reply with quote

Arthanis wrote:
Code:
lspci -k

which will not only show you your current hardware, but also will show you the kernel module in use. Then you can take notes and search for their symbols in menuconfig, enable them (for sata and disk controllers built-in, not as modules), install your kernel, build modules and reboot.

I did # lspci -k
and I see a lot of stuff that don't have any modules or kernel drivers for it :/ Like the intel processor stuff in the end.
Code:
ff:00.0 Host bridge: Intel Corporation Core Processor QuickPath Architecture Generic Non-core Registers (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:00.1 Host bridge: Intel Corporation Core Processor QuickPath Architecture System Address Decoder (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
   Subsystem: Intel Corporation Device 8086

Heres the whole list. I did make some changes to my kernel after I searched up the kernel drivers/modules to see if they were built in or not, but just in case, if u can please point out the necessary changes (:
Code:
00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller (rev 12)
   Subsystem: Dell Device 0434
   Kernel driver in use: agpgart-intel
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 12)
   Subsystem: Dell Device 0434
   Kernel driver in use: i915
00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series Chipset HECI Controller (rev 06)
   Subsystem: Dell Device 0434
00:1a.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 06)
   Subsystem: Dell Device 0434
   Kernel driver in use: ehci-pci
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 06)
   Subsystem: Dell Device 0434
   Kernel driver in use: snd_hda_intel
00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 (rev 06)
   Kernel driver in use: pcieport
00:1c.1 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 2 (rev 06)
   Kernel driver in use: pcieport
00:1c.5 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 6 (rev 06)
   Kernel driver in use: pcieport
00:1d.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 06)
   Subsystem: Dell Device 0434
   Kernel driver in use: ehci-pci
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev a6)
00:1f.0 ISA bridge: Intel Corporation Mobile 5 Series Chipset LPC Interface Controller (rev 06)
   Subsystem: Dell Device 0434
00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series Chipset 4 port SATA AHCI Controller (rev 06)
   Subsystem: Dell Device 0434
   Kernel driver in use: ahci
00:1f.3 SMBus: Intel Corporation 5 Series/3400 Series Chipset SMBus Controller (rev 06)
   Subsystem: Dell Device 0434
00:1f.6 Signal processing controller: Intel Corporation 5 Series/3400 Series Chipset Thermal Subsystem (rev 06)
   Subsystem: Dell Device 0434
03:00.0 Network controller: Broadcom Corporation BCM4312 802.11b/g LP-PHY (rev 01)
   Subsystem: Dell Wireless 1397 WLAN Mini-Card
   Kernel driver in use: b43-pci-bridge
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev 02)
   Subsystem: Dell Device 0434
   Kernel driver in use: r8169
ff:00.0 Host bridge: Intel Corporation Core Processor QuickPath Architecture Generic Non-core Registers (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:00.1 Host bridge: Intel Corporation Core Processor QuickPath Architecture System Address Decoder (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
   Subsystem: Intel Corporation Device 8086
ff:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
   Subsystem: Intel Corporation Device 8086
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PostPosted: Wed Aug 06, 2014 12:20 am    Post subject: Reply with quote

ShanaXXII wrote:
Code:
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 12)
   Subsystem: Dell Device 0434
   Kernel driver in use: i915

00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series Chipset HECI Controller (rev 06)
   Subsystem: Dell Device 0434

00:1a.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 06)
   Subsystem: Dell Device 0434
   Kernel driver in use: ehci-pci

00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 (rev 06)
   Kernel driver in use: pcieport

00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series Chipset 4 port SATA AHCI Controller (rev 06)
   Subsystem: Dell Device 0434
   Kernel driver in use: ahci


I think the key pieces here are the ones I've filtered above.

i915:
To have your high-resolution console available as quickly as possibly (which can be useful when debugging issues), you may want this built in to your kernel. That being said, some people recommend keeping this built as a module; in which case you want to ensure you have the VGA_CONSOLE option enabled - you need some sort of console available should anything happen.

ahci:
This is the key piece - the driver for the chipset controlling your hard disks - you need this built in. Additionally, you need the driver for your root filesystem built in to the kernel as well.

pcieport:
This is somewhat dependent on your actual hardware configuration - if you have any boot-critical devices attached to the PCI subsystem, then you need this driver built-in.

ehci-pci:
Not so critical, but can be useful if you need to use the keyboard before the filesystem is loaded (and, obviously, if you have a USB keyboard).

One thing that I'm not sure of is the "HECI Controller" - I don't know exactly what that is. That being said, it doesn't have a driver loaded in the live environment, so we can assume it's not critical to your boot process. For what it's worth, though, I did find a page [1] suggesting using the "mei" driver.

[1] http://h-node.org/hostcontrollers/view/en/871/Intel-Corporation-5-Series-3400-Series-Chipset-HECI-Controller--rev-06-
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ShanaXXII
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PostPosted: Wed Aug 06, 2014 2:40 am    Post subject: Reply with quote

Sorry, but my dad got angry and said that
linux is a 'waste of time' and forced me to wipe all my Linux stuff ),:< T_T
-sad :( -angry :evil:
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PostPosted: Wed Aug 06, 2014 3:31 am    Post subject: Reply with quote

Thas is sad. Tell that to your dad when you are making 6 figures as a sysadm / IT chief. Anyway, I think its worth to install some VM to play around with linux.

Anyway, about the missing drivers, I advice you to get a distro that has A LOT of modules that are then auto loaded using udev hardware detection, like ubuntu and sysrescue cd. Good luck.
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PostPosted: Wed Aug 06, 2014 3:33 am    Post subject: Reply with quote

ShanaXXII wrote:
Sorry, but my dad got angry and said that linux is a 'waste of time' and forced me to wipe all my Linux stuff

ShanaXXII ... sorry to hear that. Having graduated from taking apart vacuum cleaners, stereo systems, bicycles (and pretty much *anything* with moving parts) my parents were releaved when I developed an interest in other things (or more accurately *not* dismantling things they relied on). My parents were probably (no, definitely) more tollerant than most ITR and thankfully let those urges exhaust themselves but I wonder what I would have "wasted my time" on were this not the case and what kind of person I would be had they been less understanding. Up until they both passed on they were able to turn the tables by calling me at all hours day and night and relating how something or other is "on the blink" and would I come over and take a look, so, they probably were right not to make too much of it at the time.

Anyhow, the above is silly ... you can not waste time, only use it.

best ... khay
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PostPosted: Wed Aug 06, 2014 3:40 am    Post subject: Reply with quote

Sorry to hear your dad don't appreciate computers.

If you really like computers I suggest you have a conversation (or have him look up) what Linux is used for. It is the dominate server OS and it is the primary OS used in CS research. In physics basically all of our computing infrastructure uses Linux.

If you have any aspirations to work with computers professionally, any amount of time spent learning Linux is time well spent.
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ShanaXXII
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PostPosted: Wed Aug 06, 2014 5:39 pm    Post subject: Reply with quote

Arthanis wrote:
Thas is sad. Tell that to your dad when you are making 6 figures as a sysadm / IT chief. Anyway, I think its worth to install some VM to play around with linux.
Anyway, about the missing drivers, I advice you to get a distro that has A LOT of modules that are then auto loaded using udev hardware detection, like ubuntu and sysrescue cd. Good luck.

Yeah, guess I'll take a crack at virtualbox or something.
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PostPosted: Wed Aug 06, 2014 5:42 pm    Post subject: Reply with quote

The Doctor wrote:
Sorry to hear your dad don't appreciate computers.
If you really like computers I suggest you have a conversation (or have him look up) what Linux is used for. It is the dominate server OS and it is the primary OS used in CS research. In physics basically all of our computing infrastructure uses Linux.
If you have any aspirations to work with computers professionally, any amount of time spent learning Linux is time well spent.

My dad actually used to be a computer engineer and stuff. He's got stacks of books on Unix and Linux etc. But after moving to Canada, he had to do other jobs to get a living. Now he's basically out-dated with computers. So he doesn't really want me to do the same thing --> He feels I'm gonna have to constantly learn more and its gonna be very hard to keep up.
Hes switched careers now into the medical field. :\
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PostPosted: Wed Aug 06, 2014 6:14 pm    Post subject: Reply with quote

ShanaXXII,

Install Virtualbox on windows - I guess you are not a Mac user.

Virtualbox is a program that emulates a PC on your PC, from the BIOS on up.
Its not a true emulator, in that programs running in Virtualbox actually run on your CPU, so you don't get the slowdown that goes with emulating a CPU at the register level.

With VBox installed, wake a virtual machine with say 1G RAM and 40G hard drive. The hard drive will actually be a file on the host filesystem.

Use Virtualbox to boot System Rescue CD then install Gentoo as you would normally.

There is a small trap for the unwary. Virtualbox emulates hardware too, so when you run lspci inside Virtualbox, you see its emulated hardware, which is nothing like your real hardware.
When you install your Gentoo, you install for the hardware that lspci tells that virtualbox provides.

Tell your dad that set top boxes, TVs, DVD players etc. are Linux. Android is Linux. ChromeOS is Linux, most routers are Linux.
You are surrounded by it in your home and are mostly unaware of it.

To make a kernel that can boot without an initrd You need the following built in.
The code to read your partition table
Code:
[*]   PC BIOS (MSDOS partition tables) support (NEW)
[*]   EFI GUID Partition support (NEW)
are good choices
The code to allow the kernel to reach your HDD
Code:
< > ATA/ATAPI/MFM/RLL support (DEPRECATED)  ---
<*> Serial ATA and Parallel ATA drivers (libata)  --->
That first one must be off.
On the
Code:
SCSI device support  --->
menu you need
Code:
<*> SCSI disk support

Everything is treated as SCSI, google will give you the history lesson.
On the
Code:
<*> Serial ATA and Parallel ATA drivers (libata)  --->
you will need the options for your hard drive controller. lspci will tell you what that is.
If you have several different hard drive controllers, build them all in.
On the
Code:
File systems  --->
Make your root filesystem built in.
Thats the bare minimum.

It boils down to four rules of thumb. Go through every menuconfig option reading the help.
1. if its needed to boot set it to <*>
2. if its needed after boot, set it to <*> or to <M>
3. If you want to play with it, set it to <M>
4. If the help doesn't help, leave it alone.

Oh. You can run several instances of Virtual Box at the some time. Its not a good idea to allow VirtualBox (all instances together) to have all of your RAM or all of your CPU cores.
The host operating system will need to run too. It does work. The guests are just programs that get swapped to the page file, this makes them run very slowly.
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PostPosted: Wed Aug 06, 2014 6:20 pm    Post subject: Reply with quote

ShanaXXII wrote:
So he doesn't really want me to do the same thing --> He feels I'm gonna have to constantly learn more and its gonna be very hard to keep up.

ShanaXXII ... and your dad is basically right, but this is true of any field ... including medicine. That is somewhat besides the point however because its not simply the content of what you're learning but the way you apply yourself and all the subsidiary effects of learning (ie, the application of logic to a problem, etc). These constitute tacit knowledge and are things you only learn via application, practice, etc. Tacit knowledge is very difficult to quantify and even more difficult to place in some schema of how it might pan out in the job market. I started with dismantling vacuum cleaners, got a PhD in philosophy, and now earn my living as an editor ... there is no real trajectory there, but I'm sure each part (or other parts omitted) adds something to the whole.

best ... khay
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PostPosted: Wed Aug 06, 2014 7:06 pm    Post subject: Reply with quote

Well, I guess that it is true that in Computer Science, you have to be constantly learning and keeping up with new trends, but it is also true that if you know the basics and truly understand what you do, it is a lot easier to keep up. Most concepts in computing are still here since the 1970s, you just change their implementation.

Anyway, I don't think that virtualizing gentoo is a good way to learn, since the kernel won't have access to your hardware and will take loooong times to build stuff, it will be a drag.

I see 2 options for you: Use another distro besides gentoo in a virtualized environment. However you won't be running the awesomeness that is gentoo, and it is by far the best distro to learn stuff about linux. Most knowledge acquired using gentoo can be used in any other distro. Gentoo introduced me to Linux and I can't tell you how many times my knowledge about gentoo solved problems in debian, ubuntu, centOS, etc.

The other (recommended) option is to buy any cheap and/or used x86/amd64 hardware to play around. I don't know where do you live, but you should be able to buy some old box from 2007 fairly cheap these days. Heck, my desktop is from 2007 and still running gentoo with a good performance (even running games on steam, like trine 2), sometimes even better than new computers with windows 8 crap. And thats the beauty of gentoo, it adapts to your requirements, not the other way around. Even if you have an old 32 bits hardware running around, you will still get acceptable performance, and most important, will be running current software and learning.
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PostPosted: Wed Aug 06, 2014 8:35 pm    Post subject: Reply with quote

Arthanis,


Arthanis wrote:
Anyway, I don't think that virtualizing gentoo is a good way to learn, since the kernel won't have access to your hardware and will take loooong times to build stuff, it will be a drag.

The system being virtualised can't tell. The kernel sees the virtual hardware and the leaning is just a valid as it is on real hardware.

Yes, there are performance impacts - The HDD is a file on another filesystem, so there are two layers of filesystem code to work through. Sure, you can give VBox access to a partition but if that was an option, so is dual booting.
The other performance impact is when VBox has to intercept the guest kernel trying to execute priviledged instructions.

The whole idea is to have a safe sandpit to play in. Some performance sacrifice is , in my opinion, a price worth paying.

Is real seven year old hardware faster than VBox?
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PostPosted: Wed Aug 06, 2014 9:22 pm    Post subject: Reply with quote

Well, I don't have the actual numbers, but I do believe that vbox emulated environment would be indeed slower than a hardware from 2007 (specially if he can get a clearance server hardware), specially if you are running it under Windows and if his hardware does not have VT-X. If you or anybody else could run benchmarks and post here, that would be great.

Beside that, I do believe that there are so many interesting things you can't do in some virtualized environments. To name a few:

- Virtualization itself (Xen, Vmware, etc). Not only that, but also a paravirtualized linux under Xen is also nice to learn
- Software Raid and different filesystems such as ZFS and BTRFS. There are some nice and useful disks and filesystems setups that are impractical under a virtualized guest
- Limited I/O and network throughput since its sharing its bandwidth with the host. Some emerges can be very I/O intensive
- bootloaders and multiboot setups
- Learning to discover and enable misc drivers while building his own kernel
- You can't know the performance gain on compiling everything from scratch, because of all the overhead virtualization introduces
- In some virtualized environments , I don't know if you can enable and test different native compilation optimization flags, due to not having access to all cpu instructions set.
- 3D accelerated desktop and gaming. Although I think its possible with some solutions, it will surely be harder to do and probably less performing.
- Disk and power management

Maybe some of the things I cited may be circumvented, but nonetheless, in my opinion it will degrade the learning experience in such a "low level" distro as gentoo. I think that Virtualization is more suited to learning thinks like userland software such as SAMBA, webservers, etc, but not so much with compilations, kernel and disk/fs management.



http://www.ebay.com/itm/Dell-PowerEdge-M600-Blade-Server-2xQuad-Core-Xeon-3-0GHz-16GB-RAM-2x73GB-SAS-/310918369614?pt=COMP_EN_Servers&hash=item48642dd14e


Just my 2 cents.
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ShanaXXII
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PostPosted: Wed Aug 06, 2014 10:51 pm    Post subject: Reply with quote

Thank you everyone! I really appreciate your support (:
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NeddySeagoon
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PostPosted: Thu Aug 07, 2014 5:48 pm    Post subject: Reply with quote

Arthanis,

I agree with much of what you say. I don't have VBox benchmarks as I use KVM for Gentoo on Gentoo. I do use Vbox for XP on Gentoo but thats no use for benchmarking.
The object here is low cost learning, rather than the need for speed.

A few details
Arthanis wrote:
- Software Raid and different filesystems such as ZFS and BTRFS. There are some nice and useful disks and filesystems setups that are impractical under a virtualized guest
Software raid is fine inside Vbox. It may not actually be useful, if the host only has a single hard drive but the learning experience is valid.
Indeed, if the host uses the FAT filesystem, with its 2G filesize limit, you must use linear raid to stitch 2G chunks together to install Gentoo an a larger contiguous filesystem.
Any filesystem works too. A journalled filesystem insite a file on a Journaled filesystem is always a bad idea from a speed perspective but it operates normally, at least, until something fails.

Arthanis wrote:
- bootloaders and multiboot setups
work normally. You don't usually do multiboot inside VBox, you run another instance, but it works.

Arthanis wrote:
- In some virtualized environments , I don't know if you can enable and test different native compilation optimization flags, due to not having access to all cpu instructions set.
Virtualbox does not emulate the CPU. Your code runs natively on the CPU. You appear to have access to the full CPU instruction set too.
The virtuliser tricks the guest when it tries to use a priviledged instruction, but the code runs unmodified as a guest. This bit is slow but the lessons learned remain valid on real hadware.
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NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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