Re: CVS commit: src/sys

[David Holland <dholland-sourcechanges%netbsd.org@localhost>]

On Wed, Mar 24, 2010 at 06:41:38AM -0700, Chuck Silvers wrote:
 > > > fix copy{in,out}{,str}() to return the error returned by uvm_fault().
 > > > fixes PR 41813.
 > > 
 > > Do you know if/how this will affect PR 11904? What happens now on EIO
 > > in a memory-mapped file?
 > 
 > this change doesn't affect application mappings, only kernel mappings.
 > the user-mode equivalent of the kernel-mode pcb_onfault stuff is
 > to install a signal handler for SIGSEGV, as you described in the PR.

Well... yes, but I guess I don't understand how the read() in the PR
would end up trapping in copyin/copyout. Presumably there's a uiomove
in there somewhere, but I would have thought it wouldn't reach it at
all if the I/O failed.

I suppose I ought to wade through genfs_getpages in more detail
sometime...

 > hmm, there's an si_errno field in struct siginfo, but it looks like
 > we currently only use it for emulations... we could put the errno
 > returned from uvm_fault() in there too so that applications could
 > print a more specific error message.

That would be handy for tail, indeed.

-- 
David A. Holland
dholland%netbsd.org@localhost