Messages in this thread |  | | Date | Wed, 18 Dec 2013 11:51:30 -0600 | From | Rob Landley <> | Subject | Re: [PATCH] use initmpfs even if there's root= cmdline |
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On 12/12/13 20:38, Dave Young wrote: > On 12/12/13 at 05:25pm, Dave Young wrote: >> >> Current code use ramfs instead of tmpfs for stub when root= defined. >> >> But for real use case with initramfs, usually there's like cmdline like >> root=UUID=$UUID the root dev is the real device. For that case we have >> no way to use initmpfs, thus this patch removes the limitation so tmpfs >> can benefit more people.
The reason I did that was if you specify a root= then you don't want to _stay_ on rootfs. You specify root= so either the kernel does switch_root for you, or so rootfs does a swich_root at the end.
The point of initmpfs is that when rootfs _is_ the "real" root device, it can benefit from being tmpfs. When you're just goign to switch to a different root device, tmpfs doesn't make much difference.
> Discussed with Vivek Goyal about the kdump use case, I missed one thing that > tmpfs has default size limit though we can tune it. > > So I will think more about it, will address this later, please ignore this > patch.
I have a vague todo item of feeding rootflags= through to initmpfs, but that's really intended to specify flags for root=. There isn't really an existing command line option to specify initramfs flags because ramfs doesn't care.
It was one of those "only parse rootflags= for initmpfs when there's no root=" vs "create a new rdrootflags= ala rdinit= even though that's a subtly wrong name these days..." and it went on the todo list because neither approach was obviously superior.
Happy to take suggestions and whip up a patch if this is inconveniencing somebody. :)
> Thanks > Dave
Rob
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