Date: Tue, 24 Aug 2010 07:56:08 -0700 From: Marcel Moolenaar <xcllnt@mac.com> To: Bakul Shah <bakul@bitblocks.com> Cc: "freebsd-arch@FreeBSD.org" <freebsd-arch@FreeBSD.org> Subject: Re: RFC: enhancing the root mount logic Message-ID: <760A97A4-62D2-4900-915D-CA5D889855E1@mac.com> In-Reply-To: <20100824043344.CA4DE5B56@mail.bitblocks.com> References: <AFBE2FCA-30A6-4E1D-A964-AC4DC4C843EB@juniper.net> <20100823.171201.107001114053031707.imp@bsdimp.com> <8C76250B-E272-4807-BD0D-9F50D0BC5E10@mac.com> <20100824002350.042A45B3B@mail.bitblocks.com> <4CB9F7C8-39E8-4C3B-A3F8-A5A9EC178E7D@mac.com> <20100824043344.CA4DE5B56@mail.bitblocks.com>
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On Aug 23, 2010, at 9:33 PM, Bakul Shah wrote: > On Mon, 23 Aug 2010 18:24:07 PDT Marcel Moolenaar <xcllnt@mac.com> wrote: >> >> On Aug 23, 2010, at 5:23 PM, Bakul Shah wrote: >> >>>> The 2 reasons for doing this in the kernel are: >>>> 1. resiliency against ABI changes. >>>> 2. allowing /sbin/init to come from the actual root file system. >>>> >>>> Both points are impossible to handle efficiently or correctly if >>>> you need user space support in getting to your actual root file >>>> system. You basically have a catch-22 or bootstrap problem, which >>>> a pure in-kernel solution doesn't have. >>> >>> How about just bundling a small compressed ramfs with the >>> kernel. The kernel unpacks it, uses it as the initial rootfs >>> and runs init from it. A forth/scheme/lua based program >>> wouldn't add more than a % or so (given that the GENERIC >>> kernel is over 10MB now!). > > BTW, a friend tells me this is what Linux does (or more > likely, what they used in their server startup). I see your point and buy into the argument, but not entirely. I explicitly mentioned "embedding" and so far your arguments include things like GENERIC being 10MB or Linux server startup. We're not exactly discussing the same thing are we? I'm perfectly happy to say that the ramdisk approach is the most generic and solution for desktop and server machines but I'm not at all ready to have it include embedded systems just yet. It's just too heavy weight... -- Marcel Moolenaar xcllnt@mac.com
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