Messages in this thread | | | Date | Sat, 2 Jul 2005 10:22:18 +0200 | From | Willy Tarreau <> | Subject | Re: updating kernel to 2.6.13-rc1 from 2.6.12 + CONFIG_DEVFS_FS + empty /dev |
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Hi Eric,
On Sat, Jul 02, 2005 at 09:22:20AM +0200, Eric Valette wrote: > Greg KH wrote: > > > Why? Why not put it in ROM with your kernel image, look at how the > > kernel build process does it with the "built-in" initramfs. > > Well, nowadays, most system have only flash because ROM does not enable > to do firmware upgrade. Second, putting it in the kernel or as a > separate flash section or in an initrd does not change the problem : > something has to be stored on non volatile memory whereas you do not > need that for devfs (except devfs code itself of course) but then you > have udev instead of devfs...
Well, although I've never used udev because I've been using sort of an equivalent called "preinit" for 4 years now, I don't totally agree with you about the firmware upgrade : when you package your systems to allow the customer to perform "firmware" upgrades, your image is already very specific to a hardware model, and I don't see why you would need to create /dev entries independantly from the kernel or rootfs. Speaking for myself, my .preinit script which describes how to fill /dev entries is on the rootfs and does not need to change once packaged.
However, I agree that I encountered difficulties using this system on more generic hardware, because sometimes the raid devices did not exist, or things like this caused trouble.
IMHO, a generic system should use a full /dev directory and an embedded system should use just the strict minimum necessary for the specific hardware to run.
> > I boot my boxes with nothing in /dev and have been for almost a year > > now. udev works just fine for this, and so do some other programs that > > work like udev does. > > Nothing in /dev but with initramfs. Same cost... > > BTW : valette@tri-yann->df /dev > Filesystem 1K-blocks Used Available Use% Mounted on > tmpfs 10240 2876 7364 29% /dev > > > 2 MB RAM on my PC??? I must be missing something.
I think something went wrong, perhaps something like
# some_prog >/dev/null
while null did not exist. My /dev is a tmpfs too, but mounted with size=0, so that I can only create inodes into it, but cannot write any data. One other advantage of using size=0 is that "df" does not show it by default.
Cheers, Willy
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