| 1 |
On Tue, Dec 18, 2012 at 9:33 AM, Alan McKinnon <alan.mckinnon@×××××.com> wrote: |
| 2 |
> On Tue, 18 Dec 2012 09:08:53 -0500 |
| 3 |
> Michael Mol <mikemol@×××××.com> wrote: |
| 4 |
> |
| 5 |
> |
| 6 |
> This sentence summarizes my understanding of your post nicely: |
| 7 |
> |
| 8 |
>> Now, why is /usr special? It's because it contains executable code the |
| 9 |
>> system might require while launching. |
| 10 |
> |
| 11 |
> Now there are only two approaches that could solve that problem: |
| 12 |
> |
| 13 |
> 1. Avoid it entirely |
| 14 |
> 2. Deal with it using any of a variety of bootstrap techniques |
| 15 |
> |
| 16 |
> #1 is handled by policy, whereby any code the system might require |
| 17 |
> while launching is not in /usr. |
| 18 |
|
| 19 |
This is the solution I favor. Systemic structure which allows |
| 20 |
dependency leakage is indicative (to me) of lack of foresight and |
| 21 |
proper component role limitation, and ought to be fought. |
| 22 |
|
| 23 |
> |
| 24 |
> #2 already has a solution, it's called an init*. Other solutions exist |
| 25 |
> but none are as elegant as a throwaway temporary filesystem in RAM. |
| 26 |
|
| 27 |
I find virtually nothing elegant about a temporary filesystem in RAM. |
| 28 |
It duplicates code that already exists on the system, and it |
| 29 |
represents and additional maintenance step in system upgrades. It |
| 30 |
seems almost a given that if someone is keeping multiple kernel images |
| 31 |
on a system, they're not updating the initr* for each when binaries |
| 32 |
that would be found in each are upgraded or rebuilt. |
| 33 |
|
| 34 |
In Debian, Ubuntu and others, this is handled by a post-install hook |
| 35 |
where the initr* image is rebuilt. To me, this honestly feels like a |
| 36 |
hack. In something like Gentoo, I'd rather see package placement |
| 37 |
driven by whether or not it will be needed to get all mount points |
| 38 |
mounted. If that means i18n databases under something like /boot/data, |
| 39 |
that seems reasonable. To me, the only cases where initr* feels like |
| 40 |
the right solution are things like netboot or booting from read-only |
| 41 |
media. |
| 42 |
|
| 43 |
> |
| 44 |
> I should be clear that I do not necessarily support Lennart's |
| 45 |
> solutions, but I do support his perception of the problem (at least |
| 46 |
> partially). We cannot support situations where *launch* code is |
| 47 |
> haphazardly scattered in location X and this must always work for all |
| 48 |
> values of X. We already have a remarkably parallel situation in /boot - |
| 49 |
> in order to boot at all, the code running at that point in time needs |
| 50 |
> to be able to find stuff, and it finds it (by policy) in what we will |
| 51 |
> later call /boot. I see this /usr debate as the same thing on a larger |
| 52 |
> scale. |
| 53 |
|
| 54 |
-- |
| 55 |
:wq |
Archives