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    DateSun, 30 Jul 2006 11:48:41 -0700
    From"H. Peter Anvin" <>
    SubjectRe: [PATCH] initramfs: Allow rootfs to use tmpfs instead of ramfs
    Hugh Dickins wrote:
    > On Sun, 30 Jul 2006, Al Boldi wrote:
    >> Replugs rootfs to use tmpfs instead of ramfs as a Kconfig option.
    > 
    > Why?  Looking further down we see what you should have explained here:
    >> + This option switches rootfs so that it uses tmpfs rather than ramfs
    >> + for its file storage.  This makes rootfs swappable so having a large
    >> + initrd or initramfs image won't eat up valuable RAM.
    > 
    > Now, I'm far from an expert on initramfs and early userspace, but my
    > understanding is that the "init" of a (properly designed) initramfs
    > would pretty much "rm -rf" everything in the initramfs before passing
    > control to the final "init".  So (almost?) no valuable RAM is eaten
    > up, nor the less valuable swap if you do extend this to tmpfs (unless
    > something gets left open, which I think should not be the case).
    > 
    > So I'm inclined to say that this patch is simply unnecessary.  But
    > if people who know better think it's a good thing, I've no objection
    > (though I've not tried it): the Kconfiggery looks more likely to
    > provoke argument than the tmpfs/ramfs mods.
    > 
    
    Well...
    
    There is some justification: embedded people would like to load 
    inittmpfs and then continue running.
    
    The main issue -- which I am not sure what effect this patch has -- is 
    that we would really like to move initramfs initialization even earlier 
    in the kernel, so that it can include firmware loading for built-in 
    device drivers, for example.
    
    Thus, if this patch makes it harder to push initramfs initialization 
    earlier, it's probably a bad thing.  If not, the author of the patch 
    really needs to explain why it works and why it doesn't add new 
    dependencies to the initialization order.
    
    Saying "this is a trivial patch" and pushing it on the -stable tree 
    doesn't inspire too much confidence, as initialization is subtle.
    
    	-hpa
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