Hello,

I did the tests requested, here is the trace of my manipulations:
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christophe@altair:~$ cd Téléchargements/
christophe@altair:~/Téléchargements$ ll *deb
-rw-rw-r-- 1 christophe christophe 12261522 août   6 18:45 linux-image-3.6.0-030600rc1-generic_3.6.0-030600rc1.201208022056_amd64.deb
-rw-rw-r-- 1 christophe christophe 24295412 août   6 18:45 linux-image-extra-3.6.0-030600rc1-generic_3.6.0-030600rc1.201208022056_amd64.deb
christophe@altair:~/Téléchargements$ sudo dpkg -i *.deb
[sudo] password for christophe:
Selecting previously unselected package linux-image-3.6.0-030600rc1-generic.
(Lecture de la base de données... 200045 fichiers et répertoires déjà installés.)
Dépaquetage de linux-image-3.6.0-030600rc1-generic (à partir de linux-image-3.6.0-030600rc1-generic_3.6.0-030600rc1.201208022056_amd64.deb) ...
Done.
Selecting previously unselected package linux-image-extra-3.6.0-030600rc1-generic.
Dépaquetage de linux-image-extra-3.6.0-030600rc1-generic (à partir de linux-image-extra-3.6.0-030600rc1-generic_3.6.0-030600rc1.201208022056_amd64.deb) ...
Paramétrage de linux-image-3.6.0-030600rc1-generic (3.6.0-030600rc1.201208022056) ...
Running depmod.
update-initramfs: deferring update (hook will be called later)
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
update-initramfs: Generating /boot/initrd.img-3.6.0-030600rc1-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.6.0-030600rc1-generic
Found initrd image: /boot/initrd.img-3.6.0-030600rc1-generic
Found linux image: /boot/vmlinuz-3.2.0-27-generic
Found initrd image: /boot/initrd.img-3.2.0-27-generic
Found linux image: /boot/vmlinuz-3.2.0-23-generic
Found initrd image: /boot/initrd.img-3.2.0-23-generic
Found memtest86+ image: /boot/memtest86+.bin
done
Paramétrage de linux-image-extra-3.6.0-030600rc1-generic (3.6.0-030600rc1.201208022056) ...
Running depmod.
update-initramfs: deferring update (hook will be called later)
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
update-initramfs: Generating /boot/initrd.img-3.6.0-030600rc1-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 3.6.0-030600rc1-generic /boot/vmlinuz-3.6.0-030600rc1-generic
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.6.0-030600rc1-generic
Found initrd image: /boot/initrd.img-3.6.0-030600rc1-generic
Found linux image: /boot/vmlinuz-3.2.0-27-generic
Found initrd image: /boot/initrd.img-3.2.0-27-generic
Found linux image: /boot/vmlinuz-3.2.0-23-generic
Found initrd image: /boot/initrd.img-3.2.0-23-generic
Found memtest86+ image: /boot/memtest86+.bin
done
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With this new kernel, the system boots with some "texts glitch".

With the workaround I found (mentioned above), the wifi connects without problem.
When I remove the workaround, the same bug is back again :-(

I will remove this kernel hoping to find my system OK.
So I'll mark the bug as confirmed and not fixed in mainline kernel.

I hope I understood your instructions and have helped you.

Best regards