Messages in this thread | | | Date | Sat, 6 Nov 2004 00:14:28 +0100 (CET) | From | Grzegorz Kulewski <> | Subject | Re: support of older compilers [u] |
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On Sat, 6 Nov 2004, Martin Schlemmer [c] wrote:
> On Fri, 2004-11-05 at 22:59 +0100, Grzegorz Kulewski wrote: >>> The kernel does do more these days than it did in '95. But 6 times more? I >>> dunno.. >> >> Can't we remove ramfs for a good start? Everyone should use tmpfs instead >> and some stupid distributions (I will not tell their names) try to mount >> ramfs on /dev (udev) and that leads to very stupid panic if you will >> write for example: >> >> dd if=/dev/evms/sda5 of=/dev/sda17 bs=1024 >> >> instead of "of=/dev/evms/sda17". >> >> Explanation (if anybody needs one): >> Kernel can't create more partition devices than 15 for SCSI and SATA disks >> because of lack of minor numbers. So I am using evms to create these >> devices. So I should use /dev/evms/sda* for these partitions. And if I >> will not remember to do so then I will get oom panic very shortly because >> ramfs is not limited (in contrary to tmpfs). >> >> And this kind of stupid mistake can happen. It happened to me 3 times in a >> row before I started to debug what is wrong with this kernel. >> >> [BTW. Does somebody know how to tell the kernel that I do not want >> /dev/sda[0-9]* files (but I do want /dev/hda files) created == I do not >> want kernel partition driver to touch this particular device?] >> > > So basically /dev/sda* have major of scsi, and /dev/evms/sda* have major > of evms, and you end up using the wrong nodes?
Not exactly. I end up creating really big, growing, file on no limit RAM backed filesystem. EVMS locks standard devices, so I probably can not run something like:
dd if=/dev/sda5 of=/dev/sda6 bs=1024
because it will return "device busy" error or something like that. But I didn't test it. But I tested (in the most painful way) that
mount -t ext2 /dev/sda5 /mnt/foo
will not work because of this error.
And EVMS has no major numbers. It is purely user space. It uses device-mapper for creating devices and uses device-mapper's major number.
And yes, I probably can force UDEV to stop creating /dev/sda[0-9]* devices, but this is not the right solution I think. These config files are managed by my distribution and are complicated. I do not want to have to merge them with updates every time new UDEV is released. Besides I want to disable kernel partition discovery just for this device. This will be ugly excaption.
Thanks,
Grzegorz Kulewski
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