Re: [patch] i386, vdso=[0|1] boot option and /proc/sys/vm/vdso_enabled

[Zachary Amsden]

Zachary Amsden wrote:
> Andrew Morton wrote:
> > vmm:/home/akpm# echo 1 > /proc/sys/vm/vdso_enabled vmm:/home/akpm# 
> > vmm:/home/akpm> ls -l
> > zsh: segmentation fault  ls -l
> >
> >  
> > > That could tell us whether it's an init bug or a glibc bug.
> > >     
> >
> > It tells us neither.  This could be a new kernel bug which only 
> > certain old
> > userspace setups are known to trigger.  Until we know exactly why 
> > this is
> > occurring, we don't know where the bug is.
> >
> > And once we've worked that thing out, and if we determine that the 
> > bug is
> > in userspace then we might be able to craft the patch in such a fashion
> > that the old userspace continues to work, which would be a win.
> >   
>
> Please try my patch - sent earlier, but attached again.  It will tell 
> you with 100% confidence if the problem is with userspace expecting 
> the vsyscall page to be at a particular address.

I should rephrase.  100% confidence - engineer stupidity factor is more 
appropriate.  I can't guarantee an absolute.  But it is my belief that 
the only kernel space mapping that could ever have been relied on by 
userspace on i386 is the vsyscall page.

Zach
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