Summary: If ACPI is not enabled but APIC is, then there is trouble on Dell Optiplex GX240. If both are enabled or if both are disabled, then everything is fine. Hello, I have a Dell Optiplex GX240 and when I boot Linux, ACPI gets set up by only acpi=ht. dmesg shows the following line: DELL GX240 detected: force use of acpi=ht Everything seemed to be fine. However, I discovered that everything is not fine. The USB controller works so slowly that copying a few (uncached) 1 megabyte large photos from a USB-enabled digital camera takes many minutes instead of a couple of seconds. I am using Linux 2.6.21.1 on a Debian 4.0 ("Etch") system. I thought that this might be related to ACPI. So I tried to boot with _only_ "acpi=force" appended to the kernel command line. Voila, the USB controller started to work at full speed and copying photos from my digital camera took only seconds. I tested the system with "acpi=force" and could not find anything which did not work. So, can we please remove Dell Optiplex GX240 from the blacklist in ..../arch/i386/kernel/acpi/boot.c ? I thought that this might be related to interrupts and APIC as well. (Note that this is APIC, not ACPI.) I tried booting with _only_ "noapic" and "nolapic" appended to the command line. Again, the USB controller started to work at full speed. If removing Dell Optiplex GX240 from the ACPI blacklist is not wanted/possible, then is there a way to disable APIC and LAPIC (note that this is APIC not ACPI) by default on Dell GX240 machines? (I.e. Can one patch the kernel so that APIC and LAPIC isn't used on these machines? - I know that I can use the noapic and nolapic options on the kernel command line.) Thank you for your attention. tarrqt __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html