Date: Tue, 13 Sep 2011 00:20:12 +0400 From: Solar Designer <solar@...nwall.com> To: owl-dev@...ts.openwall.com Subject: Re: gcc 4.6.x and kernel-2.6.18-ovz Vasiliy, On Mon, Sep 12, 2011 at 10:16:06PM +0400, Vasiliy Kulikov wrote: > OK. I just don't know how real Kir's fears are. I think their project's official position on this is just right for their project - they're reusing/revising RHEL kernels and they try to minimize the number of changes (mostly limit them to OpenVZ container virtualization). However, for our project we have other goals as well. > > I dislike using non-latest-stable gcc in Owl 4.0, and there's no other > > kernel version we can use currently while continuing to include OpenVZ > > support. > > While I don't strongly state anything, why? AFAICS in changelogs, gcc > 4.4.x has all significant features we want to use (like SSP), 4.6.x has > probably not too much important for us improved C++1X support, more > strict compile time checks, better standards conformance, and many > changes in Ada, Go, Fortran, etc.; support of new -mXXX, non-x86 archs > support/improvements, etc. In general, we should try to ship the latest stable versions of packages in Owl, except where this conflicts with our other goals. I am not convinced that we have enough of a conflict with our other goals here. As to why a user of Owl could want to have gcc 4.6.1 (or newer) rather than 4.4.5: just to run the latest stable (yes, the version number itself matters to some users), and/or for the many relatively minor enhancements (which sort of add up to a significant difference). When I compile John the Ripper with different versions of gcc, some performance difference can be seen, even between these recent versions. It's small, but it's there. Some extra warnings may be seen with newer versions, which is desirable for development. Oh, and I don't recall if code generation for AVX is even available on 4.4.5. I know it is on 4.5.0, though. One of the drawbacks of Owl so far is that we have older versions of many packages. This makes Owl unattractive for some prospective users. We need to try and improve on that. So for Owl 4.0 we have mixed goals: RHEL 6 binary and package compatibility, but newer included software versions than RHEL 6's whenever possible. For example, this should be possible for glibc due to symbol versioning. And we should be able to update package versions even further. When gcc 4.7 comes out, we should be able to update to that (or at least we should try). > I'll try to make 2.6.18 kernel compilable with gcc 4.6.1. Yes, please. But please limit your time spent on this. If it starts to take a lot of time, please stop and let me know. Also, wouldn't it make more sense to make all other packages (except for the kernel) buildable with gcc 4.6.1 first? I notice that you've already committed a couple of build fixes today, but many more are needed. Thanks, Alexander
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.