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Date:      Tue, 9 Oct 2012 13:30:47 -0700
From:      Devin Teske <devin.teske@fisglobal.com>
To:        Alexander Leidinger <Alexander@Leidinger.net>
Cc:        Devin Teske <dteske@freebsd.org>, freebsd-arch@freebsd.org
Subject:   Re: New Boot Loader Menu
Message-ID:  <A465608D-31F4-475A-9D2B-A13F1FE2C4DB@fisglobal.com>
In-Reply-To: <20121009220325.00006c9d@unknown>
References:  <0655B56F-AD43-402B-872C-568378E650F9@fisglobal.com> <20121007183433.000026a6@unknown> <DB1B1B71-84B3-4096-BE52-7630CB74762F@fisglobal.com> <20121007220100.00002d21@unknown> <D2025767-BF06-442D-8A44-316ED91EA0CD@fisglobal.com> <20121009220325.00006c9d@unknown>

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On Oct 9, 2012, at 1:03 PM, Alexander Leidinger wrote:

> On Sun, 7 Oct 2012 14:58:46 -0700 Devin Teske
> <devin.teske@fisglobal.com> wrote:
>=20
>>=20
>> On Oct 7, 2012, at 1:01 PM, Alexander Leidinger wrote:
>=20
>>> The first one is a tribute to the
>>> poor victim which gives a helping hand, he will not see the boot
>>> options in case the request is made to change the root FS. The
>>> second one is that the boot options are modifying the behavior of a
>>> given kernel (verbose messages, safe mode, acpi), while the
>>> root-fs/BE/kernel item is choosing a different kernel to boot.
>>>=20
>>=20
>> I wholly agree with the separation into 2 submenus and _why_,
>> however...
>>=20
>> Let's be careful here.
>>=20
>> Be careful to not include "kernel" in that mix.
>=20
> I included kernel in that mix, because loading a different BE/FS is
> basically loading a different kernel. While it would be nice to be able
> to chose a kernel if there are multiple in a given FS, I didn't want to
> imply this here.
>=20

You make a very astute observation here.

I'm really thinking that the "promised land" is to have a [proposed] kernel=
 selection menu dynamically enumerate all kernels available on the selected=
 root device.

I think we should discuss/explore this further at the up-coming DevSummit. =
I'm requesting time in the Talks -- I'm thinking this is perfect to add to =
my time-slot.



>> In reality, the kernel is loaded by the "start" FICL word provided by
>> loader.4th and this is done:
>>=20
>> a. before the menu is loaded and
>> b. irrespective of the menu (done regardless of whether the menu is
>> enabled or not, perhaps via setting beastie_disable=3DYES in
>> loader.conf(5))
>>=20
>> So by the time the menu is invoked, the only way to change the kernel
>> is to "unload" and subsequently load the new kernel.
>>=20
>> It should be noted that DruidBSD does not load a kernel before the
>> menu. Thus in DruidBSD, we _do_ have a kernel selection menu (the
>> overloaded "boot" FICL word in DruidBSD is coded to load $kernel
>> right before doing the real boot whereas FreeBSD's overloaded "boot"
>> FICL word simply invokes the already-loaded kernel that was loaded
>> before the menu ever started).
>=20
> Is it faster to not load the kernel (time from pushing the power
> button to the loader menu being reactive to key presses)?

Absolutely!


> If yes, it
> may be beneficial to do it the way DruidBSD is doing it (it does not
> cut the time to arrive at multi-user mode, but it improves the
> response time and has the psychological effect to let the user think
> it boots faster).

I like this idea.



> And if we want to chose a kernel from a list to boot
> from, (which I think we want), we should do it too.
>=20

I'm with you.



>> It's perhaps good that we're having this discussion out in the open
>> now, because I actually (as of yet) do not know if jpaetzel, avg, mav
>> and iX company have plans to (attempt) to allow kernel swapping in
>> the loader menu. If that is the case, we'll have to broach the topic
>> of changing that functionality to match what DruidBSD does (defers
>> kernel loading until "boot" is invoked).
>=20
> If it is not much work, I don't think we should hesitate to do it. It
> offers the possibility to make enhancements later.
>=20

Ok, let me put a patch together for review.
--=20
Devin

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