From mboxrd@z Thu Jan 1 00:00:00 1970 From: dds@aueb.gr (Diomidis Spinellis) Date: Tue, 21 Feb 2017 17:54:13 +0200 Subject: [TUHS] Mach for i386 / Mt Xinu or other In-Reply-To: <58ac5a3a.geKODIzKbcVWDsIS%schily@schily.net> References: <635c06b4-0048-4951-95ca-283c64c30fed@SG2APC01FT017.eop-APC01.prod.protection.outlook.com> <1ba0f584-6478-4332-bcae-63ac6cedf2f6@SG2APC01FT041.eop-APC01.prod.protection.outlook.com> <20170219154432.GA19243@mcvoy.com> <58ab3214.+jRaJEWVki5gYHFz%schily@schily.net> <20170220222457.GB3163@mcvoy.com> <58ac16ca.V0zEZijwK0rh0Cyr%schily@schily.net> <1487684861.1580775.887937752.698B8B60@webmail.messagingengine.com> <58ac5a3a.geKODIzKbcVWDsIS%schily@schily.net> Message-ID: <094c861a-e7ef-3e79-9d70-ada7e579d127@aueb.gr> On 21/02/2017 17:18, Joerg Schilling wrote: >> Requiring "pass through SCSI" for a CD burner violates the UNIX >> philosophy that everything is a file (which implies that reading and >> writing data be implemented, where possible, through the read and write >> system calls rather than through special interfaces specific to a device >> type). > > You are incorrectly informed: > > Writing CDs is a highly complex task. No known kernel is able to do that > internally. > > So the only useful method is to use SCSI pass through. This is an interesting point. However, controlling the C/A/T phototypesetter 20 years before writable CD-ROM appeared, was also a very complex task, yet it was accomplished through a simple device file. Controlling a voice modem is also complex, time-critical, and requires bidirectional communication. Again, voice modems were controlled through a character device file. One can envisage a CD-ROM device driver abstracting the commands required for writing CD-ROMs into a text-based interface made available though a character device. These precedents demonstrate that the SCSI pass through was an unneeded architecture-violating shortcut. Arguably, the same can also be claimed for the networking system calls. Diomidis