On 18/01/18 23:44, Cyril Brulebois wrote: > Raphael Hertzog <hert...@debian.org> (2018-01-17): >> On Wed, 17 Jan 2018, Aurelien Jarno wrote: >>> busybox is compiled with -mpreferred-stack-boundary=2 on i386 which has >>> the same effect of reducing the default stack alignment from 16 bytes to >>> 2 bytes. This comes from arch/i386/Makefile: >>> >>> | # -mpreferred-stack-boundary=2 is essential in preventing gcc 4.2.x >>> | # from aligning stack to 16 bytes. (Which is gcc's way of supporting >>> SSE). >>> | CFLAGS += $(call cc-option,-march=i386 -mpreferred-stack-boundary=2,) >>> >>> I don't really get why it is essential to prevent gcc from aligning >>> stack to 16 bytes, anyway this is a bad idea. Removing this option just >>> fixes the issue.
Hi all, I've added the busybox mailing list and Denys Vlasenko. Denys: can you explain in more detail why this is/was necessary and whether it's sensible to remove this these days, given the issues it seems to cause? > Oh wow, that's an old commit: > | commit 65b8cfb2a0b6854271dbd8baf5203896223cd4ce > | Author: Denis Vlasenko <vda.li...@googlemail.com> > | Date: Mon Jul 23 21:05:06 2007 +0000 > | > | add comment why preferred stack boundary is 4 on i386 > >> I confirm that rebuilding busybox with this option dropped fixed the issue >> for me. I uploaded a fixed busybox to Kali. I'm happy to do the same for >> Debian if it can help the current maintainers. > > Fixing it ASAP would look good to me (unless you here differently from > Chris or Christoph); it would be great to ping upstream to propagate > Aurélien's comments too. I'd like to get a response from Denys about this first but I don't have any particular objection to patching this for Debian; I just want to understand better why this was done upstream before simply reverting it. We also have a new upstream release of busybox to push into unstable, so it's tempting to roll this tweak in with that. Cheers, Chris -- Chris Boot bo...@debian.org
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