Subject: Re: PROT_EXEC mappings of vnodes -> VTEXT
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Thor Lancelot Simon <>
List: tech-kern
Date: 10/30/2001 11:45:31
On Tue, Oct 30, 2001 at 11:41:38AM -0500, der Mouse wrote:
> Even if you think crashes are a Wrong Thing, I'm still not convinced
> ETXTBUSY is ever the way to do it.  ISTM that writing to a file that
> backs a text page in use should have copy-on-write semantics: existing
> mappings of that page continue to use the old data, now backed by swap
> instead of the original vnode, and new mappings (of course) use the new
> data.  ETXTBUSY is a bit like EFAULT, it seems to me: it was a kludge
> put in to make it more convenient to implement back in the dark ages
> but which has now hung on past its usefulness.

Unfortunately, we version shared libraries, not the individual symbols
within them.  Wouldn't your scheme make it possible to get incompatible
versions of different symbols from the "same" library given a dynamic
loader that used lazy symbol resolution?

Thor Lancelot Simon	                            
    And now he couldn't remember when this passion had flown, leaving him so
  foolish and bewildered and astray: can any man?
						   William Styron