since when does ARM map the kernel memory in sections?
pwaechtler at mac.com
Wed Apr 13 14:35:55 EDT 2011
Am Mittwoch, 13. April 2011, 17:44:09 schrieb Nicolas Pitre:
> On Wed, 13 Apr 2011, Peter Wächtler wrote:
> > Am Dienstag, 12. April 2011, 21:20:14 schrieb Andrei Warkentin:
> > > How are you mounting your rootfs and what file system are you using?
> > > What sort of corruptions to the super block are you seeing?
> > It's using ext4 with metadata journalling in ordered mode.
> > I had to check "if it's the FS" - the test programs create lots of
> > directories and files while a timer is armed to issue a soft reset.
> > The partitions where the "stress tests" run on - survive it happily -
> > just the rootfs where almost nothing gets written is severly damaged so
> > that fsck.ext4 will not repair it automatically.
> SD cards are doing their own wear leveling internally and you have no
> control over it. Some blocks of data may be moved around, affecting a
> separate logical partition, even if you are not actively writing to that
> partition. Now if you cut power or reset the card while this is
> happening you'll certainly end up with data loss. Those SD cards are
> made to be both cheap and fast, meaning they're certainly not reliable
> with regards to unexpected interruptions.
> Furthermore, you should have a look at this article and referenced
> material: http://lwn.net/Articles/428584/.
Yes, I know this article - and I know about wear levelling etc.
Data loss is not the biggest problem. The capacity is huge (>>4GB) - therefore
I wouldn't want to miss journalling - but I was not involved on the decision.
Ten years ago I carefully ordered the fsync, rename on ext2 on a 64MiB
CompactFlash - worked well enough.
The vendor knows about the requirements - perhaps learned it with another
I tried to "smash" the FS without success in the past - but the rootfs was
mounted via NFS ;) And the partitions that get tortured stay intact - of
course you can say that the wear levelling switches some blocks - but I don't
Thanks for all the nice work on Linux - Russell included ;)
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