<html><head></head><body><div>On Mon, 2017-02-13 at 16:18 -0500, Phil Turmel wrote:</div><blockquote type="cite"><pre>On 02/12/2017 12:42 PM, Steve Litt wrote:
<blockquote type="cite">
On Thu, 9 Feb 2017 13:38:07 -0800
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In addition to what Alex writes in the preceding paragraph, some people
prefer not to have initramfs at all.
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Yup. Embedded guys really don't want anything extra. And they
customize their kernels to give them exactly what they want.
</pre></blockquote><div><br></div><div>HPC has similar end needs. Even a module hook takes RAM. When the hardware is not going to change over it's lifespan, a custom kernel with no extra bells or whistles is nice.</div><blockquote type="cite"><pre>
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The purpose of initramfs is ONLY to get the root partition readable
enough to process /etc (let's forget about crazycases where /etc is a
mountpoint), after which the boot process can do what it's supposed to
do: Pull itself up by the bootstraps. The initramfs' init script should
have been an easy, tiny shellscript in most cases.
</blockquote>
People all over the world want faster boot. The time spent initializing
just the devices needed to get to the boot partition and then mount its
filesystem can cover a great deal of parallel probing and discovery. In
some cases, all of it. People ask distros for faster boot times,
distros respond. So what if there is substantial complexity needed to
deliver what their customers want.
</pre></blockquote><div><br></div><div>If we could only get the HARDWARE side of the boot process faster! I've got some very new, very modern server gear that from power on to Linux boot start is measured in MINUTES (I'm looking at you IBM!). Why oh why can the BIOS store the IDs of the device tree and do a fast "give me your ID scan", ok nothing changed so send back an init command to everything to run in parallel.</div><blockquote type="cite"><pre><blockquote type="cite">
My personal observation tells me that with kernels ancient and modern
(I'm using 4.9.x right now) and everything inbetween, disk device names
are stable between boots. So personally, I might consider using the
device name in order to perhaps compile ext4 drivers into my kernel and
getting rid of the entire initramfs.
</blockquote>
If you only have one SATA controller, one connected drive, and you defer
USB module loading, you can be pretty confident that your drive name
will be consistent. Or you customize your kernel to do exactly what you
want. If you're willing to do that, you need no-one's advice.
</pre></blockquote><div><br></div><div>When there's 2 drive controllers, 2 RAID cards, 2 nics on board and 2 10G cards and a dual infinniband card, walking that PCI bus takes FOREVER.</div><blockquote type="cite"><pre>
Everyone *not* willing to customize, but using a modern kernel, needs to
use an initramfs and proper partition IDs.
</pre></blockquote><div><br></div><div>I keep swearing (more than usual) I'm gonna build by blasted tool called "shoehorn" to help squeeze into a tight boot. The basic idea is to PXE boot a generic kernel with EVERYTHING as modules, probe all hardware, report back to a master server the list of found hardware, it assembles a new kernel with nothing but what's needed or points to an existing kernel, set's up a perm PXE boot environment based on MACs and then provides the slimmest kernel and initramfs possible.</div><blockquote type="cite"><pre>
Phil
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</pre></blockquote><div><span><pre><pre>-- <br></pre>James P. Kinney III
Every time you stop a school, you will have to build a jail. What you
gain at one end you lose at the other. It's like feeding a dog on his
own tail. It won't fatten the dog.
- Speech 11/23/1900 Mark Twain
http://heretothereideas.blogspot.com/
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