On 12/27/2013 03:49 AM, Gordan Bobic wrote:
On 12/26/2013 02:20 PM, Derek Atkins wrote:
Gordan Bobic gordan@bobich.net writes:
(e.g. (but not limited to) a large number of packages make little or no effort to ensure memory accesses are aligned - including the likes of e2fsprogs, and transparent alignment fixup in hardware is only available on armv7 and later).
I'm surprised that Ted isn't willing to fix issues in e2fsprogs.
If you can point me to the upstream bug reports I can ping him to see what's up?
Take a look here: http://comments.gmane.org/gmane.comp.file-systems.ext4/33324
As has been mentioned before, there is a whole shedload of packages that have similar issues - I have seen literally thousands of alignment faults get reported (I have the alignment set to fix+warn on my armv5tel builders) in various packages during build and test stages. Once upon a time I planned to collate the data and get the issue reported to all upstream maintainers, but that is a mammoth task just to report, let alone fix, and I have very little faith there is enough will among the developers to fix all the affected packages and ensure they write code that isn't affected by this problem going forward.
This is hardly surprising, as you can't really fix what you can't test.
15 years ago my Linux/Unix code was always clear of alignment issues, as I developed on a mix of Alpha and x86 machines, and the Alphas didn't like misalignment. I think enough people developed on a mixture of machines to flush out most of the alignment issues back then.
We entered a period of such x86 dominance that few people saw alignment issues any more, and I suspect the number of issues grew rapidly. Now, non-x86 work is growing again, but its mostly on ARMv7 devices, so I think its unlikely the frequency of alignment issues will ever go down again.
Regards, Steve