A 4-byte write to an I/O port means four one-byte writes to four consecutive I/O ports (although, this can be done in one machine instruction.) >From our testing, Windows indeed is only allowing the single-byte write to the (legal) port 0x80. The rest of the request is simply ignored. In general, any part of an I/O request that overlaps the protected ports is ignored. No error is returned. We are updating ACPICA to match this behavior. Bob >-----Original Message----- >From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- >owner@xxxxxxxxxxxxxxx] On Behalf Of Matthew Garrett >Sent: Wednesday, April 08, 2009 11:24 PM >To: Len Brown >Cc: Rodrigo Luiz; malattia@xxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx >Subject: Re: [PATCH] ACPICA: delete check for AML access to port 0x81-83 > >On Tue, Apr 07, 2009 at 05:56:09PM -0400, Len Brown wrote: >> From: Len Brown <len.brown@xxxxxxxxx> >> >> Sony laptops apparently write 4-bytes (rather than 1 byte) >> to debug port 0x80, which spews error messages: > >So admittedly I should just check the spec here instead, but: what does >a 4 byte write to an io port mean? It seems a bit odd that Sonys could >be scribbling over DMA1 without causing any problems. Is Windows turning >this into a single byte write to the defined io port instead? > >-- >Matthew Garrett | mjg59@xxxxxxxxxxxxx >-- >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 -- 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
