OFW unsecure kernel/initramfs load from zip file
quozl at laptop.org
Wed Sep 21 17:39:22 EDT 2011
On Wed, Sep 21, 2011 at 04:21:42PM +0100, Daniel Drake wrote:
> One lingering question is how OFW deals with mounting/unmounting.
> I know that some words (in some contexts?) cause the disk to be
> mounted, then the command to be executed, then the disk unmounted.
Every open effectively causes a device initialisation and read of
filesystem metadata. It is one reason why external SD is so slow for
multiple operations on XO-1.5; there's a coded delay for allowing the
card supply rail to fall far enough for the card to reset.
But OpenFirmware isn't doing anything else, so the operations tend to be
> Will the previously attached code cause a lot of mounts/unmounts?
Yes. bundle-present? place-ramdisk ?ofw-reflash $file-exists?
> I'm particularly worried that it would slow down boot noticably. The
> ideal of course is that it only gets mounted once, before this code
Measure it. In stages if necessary. Enclose sections in t( )t pairs.
" last:\boot\vmlinuz" 2dup
t( $file-exists? ." time: vmlinuz existence" )t cr
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