From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: ultrastor.c is a bit-rot Date: Mon, 17 Mar 2008 11:03:06 -0500 Message-ID: <1205769786.6767.140.camel@localhost.localdomain> References: <47DE8736.8020405@panasas.com> <1205767383.6767.139.camel@localhost.localdomain> <47DE95A9.8060502@panasas.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from accolon.hansenpartnership.com ([76.243.235.52]:43840 "EHLO accolon.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751976AbYCQQDK (ORCPT ); Mon, 17 Mar 2008 12:03:10 -0400 In-Reply-To: <47DE95A9.8060502@panasas.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Boaz Harrosh Cc: linux-scsi , Andrew Morton , linux-kernel On Mon, 2008-03-17 at 18:00 +0200, Boaz Harrosh wrote: > On Mon, Mar 17 2008 at 17:23 +0200, James Bottomley wrote: > > On Mon, 2008-03-17 at 16:59 +0200, Boaz Harrosh wrote: > >> Inspecting ultrastor.c it is clear to me that this was never used for > >> a loooooooooong time. Not since a PC has more then 2^24 bit of memory. > >> Let me explain below. > >> > >> Now I'm not saying it should be fixed. I'm saying that it should be dumped > >> in the account that it is not used by any one and that it does not work. > >> > >> Why it never worked? > >> ~~~~~~~~~~~~~~~~~~~~~ > >> > >> The driver's header says it supports 3 cards > >> > >> * 14F - ISA first-party DMA HA with floppy support and WD1003 emulation. > >> * 24F - EISA Bus Master HA with floppy support and WD1003 emulation. > >> * 34F - VL-Bus Bus Master HA with floppy support (no WD1003 emulation). > >> > >> But Kconfig only specifies ISA. I'm not sure what a VL-Bus is. > > > > VL is vesa local ... it was an ISA like graphics bus that was fast and > > could reach > 16MB. > > > >> now the driver defines a static array of structures like this: > >> > >> struct { > >> ... > >> > >> struct mscp mscp[ULTRASTOR_MAX_CMDS]; > >> } config = {0}; > >> > >> and allocates a struct mscp in .queuecommand like this: > >> my_mscp = &config.mscp[mscp_index]; > >> > >> it will go on preparing this my_mscp structure including stuffing > >> some mapped pointers. Lets put that aside for now. > >> At the very end it will pass this my_mscp structure to the card's > >> firmware like this: > >> > >> /* Store pointer in OGM address bytes */ > >> outl(isa_virt_to_bus(my_mscp), config.ogm_address); > >> > >> Now this is one hell of a smart ISA card. But putting this aside. > >> > >> if the machine has more then 2^24 of memory. Then this will never > >> work, right? or I'm missing it completely? > > > > It will definitely work for EISA and VL bus. I think if you analyse the > > placement of kernel data segments for compiled in drivers, it might also > > work for ISA too, since I think the pfn will be low enough. It should > > fail as a module not just because the area will be out of range for ISA, > > but also because the module data segment is in vmalloc space, so the > > virt_to_bus assumptions of contiguity could be violated. > > > > James > > > > So what is the verdict? is it removed? marked broken for ISA? It's probably obvious enough to apply the best straight line fix. > can I safely say that unchecked_isa_dma can be removed? No ... ISA definitely requires it. James