Re: [PATCH] i386 vsyscall DSO implementation

[David Mosberger]

>>>>> On Fri, 25 Apr 2003 14:20:47 -0700, "H. Peter Anvin" <[e-mail]> said:

  hpa> David Mosberger wrote:
  >>  >> To complete the picture, it would be nice if the kernel ELF
  >> >> images were mappable files (either in /sysfs or /proc) and
  >> would >> show up in /proc/PID/maps.  That way, a distributed
  >> application >> such as a remote debugger could gain access to the
  >> kernel unwind >> tables on a remote machine (assuming you have a
  >> remote >> filesystem).

  hpa> How about /boot?
  >>  You mean a regular file?  I'm not sure whether this could be
  >> made to work.  The /proc/PID/maps entry (really: the vm_area for
  >> the kernel ELF images) would have to be created by the kernel, at
  >> a time when no real filesystem is available.  Also, since the
  >> kernel needs to store the data in kernel-memory anyhow, I don't
  >> think there is much point in storing it on disk as well.

  hpa> Perhaps I misunderstood the statement.  With "kernel ELF
  hpa> images" above, I am now gathering you're talking about only the
  hpa> segments exported to userspace (i.e. vsyscall code), not the
  hpa> kernel itself, which was my original reading of that statement.

Sort of.  I used the term "kernel ELF images" to refer to kernel code
that is shared with the user.  I thought that even on x86 this code is
pinned in memory, but perhaps I misunderstood.

Anyhow, it seems to me that using a special filesystem would be more
suitable, as otherwise you get into bootstrap problems etc.

	--david