[TUHS] Mach for i386 / Mt Xinu or other

Cory Smelosky b4 at gewt.net
Wed Feb 22 02:38:49 AEST 2017


Diomidis Spinellis wrote:
> 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.

How would you handle the different writing methods? Separate device 
files or an ioctl on a generic device node?

(not arguing - genuinely curious about your theory)

>
> 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
>



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