On Sat, 2011-11-19 at 11:05 -0800, Greg KH wrote:

On Sat, Nov 19, 2011 at 05:22:10PM +0000, Ben Hutchings wrote:

quoted

On Fri, 2011-11-18 at 16:02 -0800, Greg KH wrote:

quoted

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

[This patch is supposed to be applied in 3.1 (and maybe older) branches only.]

New kernels support newer firmware that users may try to incorrectly use
with older kernels. Display error and explain the problem in such a case

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/net/wireless/b43/main.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c

@@ -2508,6 +2508,13 @@ static int b43_upload_microcode(struct b
 		b43_print_fw_helptext(dev->wl, 1);
 		err = -EOPNOTSUPP;
 		goto error;
+	} else if (fwrev >= 598) {
+		b43err(dev->wl, "YOUR FIRMWARE IS TOO NEW. Support for "
+		       "firmware 598 and up requires kernel 3.2 or newer. You "
+		       "have to install older firmware or upgrade kernel.\n");
+		b43_print_fw_helptext(dev->wl, 1);
+		err = -EOPNOTSUPP;
+		goto error;

[...]

Again, I strongly object to this way of handling the incompatibility.
The revision check is fine, but the solution must be to assign a
different filename for the newer revisions.  The changes to 3.0/3.1
should be deferred until this is resolved.

You can object, however the driver author and maintainer wants it done
this way for now, so that's a valid solution that I have to accept.  It
solves real bugs that people have already hit when running the 3.0 and
3.1 kernels.

The revision check fixes a bug, yes.  What I'm concerned about is the
cop-out error message: 'We didn't deal with versioning properly, so you
get to solve the problem.'  It should be possible to reboot between
multiple installed kernel versions without modifying files.

Propagating a userspace tool change for those systems
would be much harder, if not impossible, don't you think? It would also
require a much more intrusive change to the driver infrastructure to
handle such a proposed change.

It is the new kernel version and firmware files that should be changed,
not the old ones.

There is another option which is to use the /lib/firmware/<kernel-ver>
directories to separate incompatible firmware versions.  That is not
nearly as good as using a API/ABI number in the filename, but it would
work and the error message could suggest it.

Ben.

-- 
Ben Hutchings
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