Re: PR/49328 CVS commit: src/sys/dev/pci/ixgbe

[christos%zoulas.com@localhost (Christos Zoulas)]

The following reply was made to PR kern/49328; it has been noted by GNATS.

From: christos%zoulas.com@localhost (Christos Zoulas)
To: Chuck Silvers <chuq%chuq.com@localhost>
Cc: 6bone%6bone.informatik.uni-leipzig.de@localhost, gnats-bugs%NetBSD.org@localhost, 
	kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, 
	netbsd-bugs%netbsd.org@localhost
Subject: Re: PR/49328 CVS commit: src/sys/dev/pci/ixgbe
Date: Sun, 1 Feb 2015 12:56:51 -0500

 On Feb 1,  9:33am, chuq%chuq.com@localhost (Chuck Silvers) wrote:
 -- Subject: Re: PR/49328 CVS commit: src/sys/dev/pci/ixgbe
 
 | that is not legal.  pmap_growkernel() is not optional for kmem allocations
 | which increase the maximum kmem address in use.
 | 
 | and before you try to dive in and make a nowait version of pmap_growkernel(),
 | let's discuss if that's the way we want to resolve this.  it's currently
 | illegal to allocate kernel memory (even with nowait/nosleep) while holding a
 | spin mutex.  if we want to keep that restriction, then we just need to change
 | this one driver to not do that.  if we want to relax that restriction,
 | there a bunch of UVM and pmap changes needed.
 
 I was not planning to do that (make a nowait version of pmap_growkernel)...
 I was questioning exactly that: if a NOWAIT allocation should fail instead
 of grabbing a mutex and only failing when LOCKDEBUG is active. Ideally code
 that always fails in LOCKDEBUG mode, should not "work by accident" in regular
 mode.
 
 This pmap_growkernel code seems strange to me because it seems that it
 is not allowed to fail (the result is not being checked in 2 of 3 places),
 and perhaps the whole thing should be abstracted...
 
 christos