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Getting Grubby & Demystifying Linux Booting
davidmwilliams writes "Linux users can boast long times between reboots, but even so, the startup screens will grace your display at some time. Here's just what your computer is doing during this process, what the messages mean, and how you can take control."
The aritcle is wery redhat specific.
When i Moderate something -1 Flamebait, why do i not get another modpoint?
5--1 = 6
Nothing new, and the author has apparently not used any other distros than the Redhat based ones. Nor has he heard about lilo or syslinux. First page of article looks like the man page of grub, listing the format for the menu.lst file of grub. Since it mentions selinux and redhat, I bet most of that page is copied more or less in verbatim from Redhat's manual. And since such a short article is split over 3 pages, and last page is laden with icons for digg, slashdot etc. I believe this is just an attempt to get some readers... Just don't bother to RTFA!
Assembling etherkillers for fun an profit
How can you have an article about init without even mentioning upstart? Ubuntu has been using it since 6.10.
Bah!
That article was just pathetic.
The concept to write an article about the boot process actually sounds cool, seeing as how there is quite a bit text that whips by on start up which many (even long time) Linux users don`t understand.
This article however, was a really lame attempt to do so. It was very general, without even so much as a sample of text from dmesg. And what was there was very distro-specific. It just provided a quick over view of the major parts of the boot process, and didn`t even do that very well.
Anyway, as someone said before, don`t even bother reading TFA..
Ever since somebody decided "Web 2.0" existed, there's been a big slew of these awful new "IT stuff" sites that look like they've been designed using a checklist of Web 2.0 mainstays and buzzwords. User ratings? Check. Submit news? Check. Blogs? Check. Annoying multipage articles? Check. Attention whoring abuse of social bookmarking sites at the end of every article? Check. More banner ads than content on any given page? Check. User comments? Check. Half of it is actually a decade old and was pioneered by Slashdot, but thanks to the magic of buzzwords, everything old is new.
And with all of this stuff in place, they invariably fail to even attempt the final hurdle: creating decent content. Instead of picking one of the two available routes (create good content vs Slashdot-style aggregation), they seem to like to go halfway, with awkward "stories" like this half-boiled Red Hat GRUB HOWTO masquerading as "Breaking News".
Sure, maybe these are probably all honest people trying to kick-start their journalism careers. But if so, what the hell are they doing throwing this crap around? Even Katz was more interesting than this trash.
As sad in previous posts this Article is about init, which is about to be obsoleted by upstart (at least in ubuntu and debian, but i think others will follow). Upstart can work as a drop-in replacement for init, and has done so in Ubuntu 6.10. Here is an old but nice Article about Linux Booting, that includes init and upstart.
I just don't trust anything that bleeds for five days and doesn't die.
[I use hibernate on Fedora all the time, so I'd love to see a patch like this go in to Fedora's grub. Thing is, the patch is apparently based on swsusp2, and I'm not sure Fedora's kernel uses the swsusp2 version of hibernation.]
In a reply to the post, a debian guy points out that grub is legacy at this point, and that they are looking to move to grub2.
I'm sure I could go into more detail by doing a little research, but in short:
GRUB is intended to be more generic than LILO and thus runs on more OSes and platforms. The developers probably got disgusted with dealing with LILO, SILO, PALO, boot0, etc... on different machines.
GLaDOS for President 2016! "Well here we are again. It's always such a pleasure." -- GLaDOS, 2011
Sigh. More climate change deniers.
Look kids, it's time to grow out of willy-waving contests about how long you can keep it up, and turn the ****ing thing off when you're not using it.
That would be a GREAT idea, if only you showed us your secret way of resuming from cold boot within 0.5 seconds when the machine recieves a tcp syn packet on port 80.
Part right, part wrong.
/etc/lilo.conf.
LILO copies a kernel image to its boot area. It doesn't matter if you change the kernel on the hard drive, because LILO's installed image won't change until you invoke the "lilo" command. I've actually seen LILO successfully boot a kernel and initrd (which panicked) after I had formatted a drive and removed all of the partitions, because I hadn't bothered to wipe the MBR.
With GRUB, however, it's live. If you make a change to your menu.lst file, that change will take effect immediately. And while admittedly, I don't use GRUB, I don't think there's actually a test utility that will tell you whether your menu.lst is properly configured without rebooting. Correct me if I'm wrong, as I frequently am. The recovery console is useful, but as I'm often tinkering with things, I prefer to have a bootloader that's static, and won't change until I explicitly tell it to. There's also the "lilo -v -t" command to test when I make a change to
If you believe everything you read, you'd better not read. - Japanese proverb
As to climate change, hell yes we're suffering climate changes but are the man-made or because we've entered the 50 year increased solar activity period of the 100 year cycle? The other question is who pays for the demanded changes and will they do any damn good? The damn research has gone about finding a solution the wrong way.
Instead of looking at how to cut energy demands by
getting rid of all parasitic electronic loads
and you'd be surprised how fast those parasitic loads add up. The simple example is a 5watt load that's on 24/7. That consumes 1kw every 8d:6h, meaning just under 3kw in a month. Check how much is being used by the tv/stereo/surround sound, digital clocks, cordless phones, cable box, printers and such and you'll get an idea why the average household now uses more then 7.5kw per month.
Now go and check all of your electronics and see if they're actually off instead of in standby before you bring up global warming again.
Mod me up/Mod me down: I wont frown as I've no crown
No, it doesn't. You can read the LILO technical documentation if you don't believe me.
The fundamental thing about LILO is that unlike Grub, it's incapable of actually reading the filesystem the kernel is on. The way it works is that the boot sector contains the location of the map file, and the map file contains the list of sectors that make the kernel. There's no "boot area" as such. It's trivial to verify that the map file isn't the kernel, as it's tiny (78KB on one of my boxes)
The reason LILO booted for you is simply because a format didn't overwrite the data areas of the disk. Since LILO doesn't read the FS itself, it doesn't matter to it that all the metadata is gone. So long the boot sector is there, the map's data is there (even without metadata indicating the filename, etc), and the kernel's data is there, it'll boot.
LILO however will completely mess up if you are unlucky. Overwriting the kernel without calling "lilo" afterwards might work if it just happens to write over the same sectors and uses the same number of them. Or maybe the new kernel is written somewhere else entirely, in which case you'll boot the old kernel and it'll break later when something reuses the space taken by the old version.
The problem with LILO is that you can screw it up without touching LILO itself. For example, delete the active kernel. It'll probably work anyway, right until something reuses the space previously taken by the kernel. Then boom, doesn't work anymore. With grub it doesn't matter if you make a bad config file, or delete a needed kernel. So long there's a kernel on disk, grub can boot it.
GRUB, unlike LILO, is able to read filesystems and recognize kernel images too
Lilo probably overcame this a while ago but there is also problem reading beyond 1024 cylinders
Some of us use the things for stuff like serving web pages. In that case a couple of hundred days between power cycles or reboots is a pretty short time.
A good way to know about the boot process is to install Linux From Scratch.
I always got annoyed about things that run on my computer that I don't know what it is, and if removing it would break anything. LFS clarified for me many dark-spots about the boot process. I even ran the installed system for almost a year, but it got harder to keep up-to-date with package versions, and I came back to using a normal distro.
factor 966971: 966971
It's technical enough to divide the Moorlocks from the complete Eloi that call the beige box on their desk a "hard drive".
No, it doesn't. When you run lilo to install a kernel, it finds out which set of physical disk blocks contain the kernel image and stores the address of those blocks in the boot area. At boot time, it loads from that address. Note that if your file system were in the habit of moving files around, it might break LILO.
I've actually seen LILO successfully boot a kernel and initrd (which panicked) after I had formatted a drive and removed all of the partitions, because I hadn't bothered to wipe the MBR.It didn't matter that the partitions were removed because LILO doesn't know or care about partitions. It was able to load the kernel because the disk blocks containing the kernel hadn't been overwritten.
I don't use GRUB, I don't think there's actually a test utility that will tell you whether your menu.lst is properly configured without rebooting.No, I don't think there is, but that's because it's not really necessary.
GRUB lets you edit the configuration from the bootloader, so if you happen to have messed up your menu.lst, it's no problem. Try to boot, see that it can't load the kernel, pop back to GRUB, look at the configuration you're trying to boot, tweak the config, try to boot that. Repeat until the system boots. In a worst-case scenario, you can even use the GRUB command line to explore the system, find a bootable kernel and boot it even with *no* menu.lst. This is better than LILO, because it even accommodates situations where the system may have changed. Being able to test your LILO config does no good if the config has been invalidated because disks have been swapped around, or if you forgot to update LILO after installing a kernel and removing the old one.
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