Date: Sat, 30 Apr 2011 22:03:38 +0300 From: Alexander Motin <mav@FreeBSD.org> To: rank1seeker@gmail.com Cc: freebsd-hackers@freebsd.org Subject: Re: Look of boot2, on HDD Message-ID: <4DBC5D0A.3080008@FreeBSD.org> In-Reply-To: <mailpost.1304185192.8734364.83157.mailing.freebsd.hackers@FreeBSD.cs.nctu.edu.tw> References: <4DBC3D63.6020508@FreeBSD.org> <mailpost.1304185192.8734364.83157.mailing.freebsd.hackers@FreeBSD.cs.nctu.edu.tw>
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On 30.04.2011 20:39, rank1seeker@gmail.com wrote:
>> Garrett Cooper wrote:
>>> 2011/4/29<rank1seeker@gmail.com>:
>>>> /boot/boot2 STAGE 2 bootstrap file
>>>> Understands the FreeBSD file system enough, to find files on it, and can provide a simple interface to choose the kernel or loader to run.
>>>>
>>>> Once sys is fully booted, HDD is 'ada0'.
>>>> However, STAGE 2, sees it, as a 'ad4', at boot process, which is same seen, by booted sys, when I turn off AHCI.
>>>>
>>>> So, here is the riddle ...
>>>> On fully booted sys, how do I query STAGE 2, to tell me, how it'll see, my 'ada0' HDD?
>>>
>>> This is a very interesting catch:
>>>
>>> /usr/src/sys/boot/pc98/boot2/boot2.c:static const char *const
>>> dev_nm[NDEV] = {"ad", "da", "fd"};
>>> /usr/src/sys/boot/i386/boot2/boot2.c:static const char *const
>>> dev_nm[NDEV] = {"ad", "da", "fd"};
>>>
>>> It probably will be a no-op soon because of some of the
>>> compatibility changes Alex made, but still a potential point of
>>> confusion nonetheless.
>>
>> Pardon my ignorance, but could somebody shed some light for me on this
>> list of names? Why much more sophisticated loader(8) operates disks as
>> diak0/1/..., while boot2 tries to mimic something he has no any idea
>> about, using very limited information from random sources? Does this
>> names important for anything?
>>
>> Even with old ATA names didn't match on my laptop: boot2 reports ad0,
>> while system - ad4. Also we have a lot of drivers who's disk names don't
>> fit into this set of ad, da and fd.
>
> Well ..., ATM, I say lets NOT touch/edit boot2 nor loader.
> Let them continue to see devices, the way they "like" ...
League for the robots rights? :)
> NOW, all I would like, is to find a way of ASKING them, how will they see "$target" device, at theirs boot step/time.
> "Asking" is done, on a fully booted sys and I am interested in asking STAGE 2 (boot2).
I think it may be impossible. It is up to each controller's BIOS to
report device or not. And some controllers may just have no/disabled
BIOS to report anything. Artificial separation between ad and da in
boot2 also doesn't makes thinks easier.
--
Alexander Motin
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