Re: [PATCH] speedy boot from usb devices

[Kalin KOZHUHAROV <kalin@thinrope.net>]

David N. Welton wrote:
> Paulo Marques <pmarques@grupopie.com> writes:
> 
> 
>>David N. Welton wrote:
> 
> 
>>>        Works like so: whenever a block device comes on line, it
>>>        signals this fact to a wait queue, so that the init
>>>        process can stop and wait for slow devices, in particular
>>>        things such as USB storage devices, which are much slower
>>>        than IDE devices.  The init process checks the list of
>>>        available devices and compares it with the desired root
>>>        device, and if there is a match, proceeds with the
>>>        initialization process, secure in the knowledge that the
>>>        device in question has been brought up.  This is useful if
>>>        one wants to boot quickly from a USB storage device
>>>        without a trimmed-down kernel, and without going through
>>>        the whole initrd slog.
>>I find this to be very useful. I always found the "sleep for a while
>>until the device we want appears" approach very cumbersome.

I hope it works. I tried to hack some delay on my own, but without success :-(
Will try this patch.

> Glad to hear someone likes it.
> 
> 
>>However, after looking at your patch, it seems that having a
>>get_blkdevs() function that alloc's an array of strings, and return
>>it to a function that only compares the strings against the name it
>>is looking for and drops the array altogether, is a little overkill.
>>Why not have a simple blkdev_exists(char *name) function in genhd.c,
>>call it directly, and drop the match_root_name() function
>>completely?
> 
> 
> Sure, that's probably better.  Maybe "blkdev_is_online"?  I'll see if
> I can do it tommorow.

Waiting :-)
I am planing to run a Gentoo-based small dist off a 128MB USB flash.

> I'm also a bit dubious of having the wait queue floating around as a
> global, but don't know the kernel well enough to find it a better
> home.

Thumbs up!

Kalin.

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