In Slackware 12 the default kernel is <code>vmlinuz-huge-smp-2.6.21.5-smp</code>, which works well except it doesn't have a module built in that's required for ACPI sleep. I won't explain why cause honestly I don't understand myself - basically the reason is the 'smp' in that kernel.<br />
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If you only have one single core processor, this is easy to fix. The process is very similar to updating the kernel from 2.4 to 2.6 in previous Slackware versions.<br />
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Go into <code>/boot</code> and, as root, do the following sequence of commands:<br />
<pre>ln -sf vmlinuz-generic-2.6.21.5 vmlinuz
ln -sf config-generic-2.6.21.5 config
ln -sf System.map-generic-2.6.21.5 System.map
mkinitrd -c -k 2.6.21.5 -m reiserfs</pre><br />
You can use <code>System.map-huge-2.6.21.5</code> instead of <code>vmlinuz-generic-2.6.21.5</code> if you like, and then you won't need to do the mkinitrd part.<br />
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If you do just copy paste those commands, you have to edit <code>/etc/lilo.conf</code> and add the line <code>initrd = /boot/initrd.gz</code> to your boot settings, so it looks like this:<br />
<pre>image = /boot/vmlinuz
  initrd = /boot/initrd.gz
  root = /dev/hda1
  label = Slackware
  read-only  # Partitions should be mounted read-only for checking
  append=&quot;acpi_sleep=s3_bios&quot;</pre><br />
Other than that Slackware 12 is pretty much the same as the previous versions. The differences good to know are: you no longer need to <code>rmmod uhci_hcd</code> when going to sleep, you don't need to <code>echo 1 &gt; /proc/acpi/sleep</code> when closing the lid, and the sound works out of the box.<br />
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Enjoy.