On Sat, 2015-11-21 at 23:22 +0100, Helge Deller wrote: > Hi Ben, > > On 21.11.2015 21:57, Ben Hutchings wrote: > > On Fri, 2015-11-20 at 22:38 +0100, Helge Deller wrote: > > > On parisc we have up to now never supported Huge Pages, even glibc did > > > not defined MAP_HUGETLB for parisc. Since the Huge Page support is being > > > added now, clean up existing definitions for MAP_HUGETLB and friends. > > > > > > Drop lots of MADV_xxK_PAGES flags, which were never used and were > > > designed for a patch which was never integrated into the Linux > > > kernel. Instead move other MADV_ flags to make them more compatible to > > > other linux architectures. > > > > Changing the unimplemented values seems fine, but how can it be OK to > > renumber MAP_GROWSUP, MADV_DONTDUMP and MADV_DODUMP? > > MAP_GROWSUP is new. > MAP_STACK changed, but doesn't seeem to be used inside the kernel anyway. It may not be implemented in the kernel, but it is certainly used by userland: https://sources.debian.net/src/glibc/2.19-20/nptl/allocatestack.c/#L513 So you can't assign any new semantics to that bit, and you might as well keep MAP_STACK as the same value. > MAP_HUGETLB is new. > > MADV_DONTDUMP and MADV_DODUMP changed, but I tend to think that they are > not widely used (if at all on parisc), and even in glibc they are only > accessible if applications included . > So, having the same value for both as all other architectures gives long-term > probably more benefits than keeping the current values. [...] This does not trump the fact that existing applications may break and that is something we generally try very hard to avoid. Ben. -- Ben Hutchings If you seem to know what you are doing, you'll be given more to do.
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