Re: recent armel/armhf kernels ENOMEM on mprotect, maxima/axiom FTBFS
On Sun, 2014-08-17 at 11:29 -0400, Camm Maguire wrote:
> Greetings! Recently, some change has been introduced into the 32bit arm
> kernels (apparently) which is blocking maxima and axiom, and perhaps
> others. These programs rely on mprotecting various pages read-only to
> accelerate garbage collection, an algorithm which has worked on arm for
> many years. Now, after a relatively few calls, mprotect returns ENOMEM,
> indicating (perhaps) that the kernel table size for this information has
> been decreased. When run under gdb, the calls succeed, which is a
> mystery to me.
>
> In any case, I can turn this algorithm off if this is likely to be a
> permanent condition on these machines. If this is rather a bug, please
> let me know if I can assist in fixing it.
I've not noticed anything of this nature going on (but I could easily
have missed it) but I have a hard time imagining that this would be
deliberate so my money would be on a bug of some sort (AFAIK there is no
"kernel table size" as such since r/w is a bit in the actual page
table).
Have you confirmed that this is a kernel change rather than a change to
maxima/axoim or some other change? Any idea with which version (or range
of versions) it started?
Ian.
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