Today I started getting errors like this on Eee:

ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata2.00: cmd ef/05:fe:00:00:00/00:00:00:00:00/40 tag 0 cdb 0x0 data 0 
         res 51/04:fe:00:00:00/00:00:00:00:00/e0 Emask 0x1 (device error)
	 ata2.00: configured for UDMA/33
	 ata2: EH complete
	 sd 1:0:0:0: [sda] 7815024 512-byte hardware sectors (4001 MB)
	 sd 1:0:0:0: [sda] Write Protect is off
	 sd 1:0:0:0: [sda] Mode Sense: 00 3a 00 00
	 sd 1:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA

That's with a stock Debian 2.6.23 kernel which I've been running since I first installed Debian.

I just hope this doesn't mean the solid state drive is already reaching its maximum number of write cycles. So far these errors don't seem to have any effect short of annoying me when I'm using the console.

Update: Mystery solved. Some browsing through kernel source revealed that "ef" is ATA command ATA_CMD_SET_FEATURES. This sounded like something hdparm would do and indeed hdparm was being run from some misconfigured ACPI scripts I forgot to clean up yesterday.