>Many BIOS ACPI tables from years ago simply _assumed_ that you have >hardcoded irq 14/15, even... Their irq descriptors for 14/15 would be >absent or completely non-functional. > >Or maybe its the $pirq table I'm recalling. One of the two, anyway. For x86, the ACPI interrupt configuration process is to identity-map the IOAPIC entries below 16 1:1 PIC:IOAPIC, unless there are interrupt source overrides (such as commonly done to swizzle IRQ0 from a different pin) This makes legacy-mode ATA happy. Hard code ATA to 14/15 and off you go. But there is a gray area where the ATA controller registers as a PCI device, but Linux goes off and looks in the ACPI PRT for that PCI-dev and finds no entry. So if you didn't have the hard-coded 14/15, you'd be dead. Then there are cases where the PRT specifies something _other_ than 14/15 for ATA, and in that cases the hard-coded default is the wrong thing to do; and the workaround is to use BIOS SETUP options to be sure that ATA is set up in legacy mode. I suspect Linux could be smarter here. The 14/15 should be the backup default for when the tables don't give us anything else; not the only option. -Len - : send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
