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SubjectRe: Blind-access patch for Linux 1.3.x
On Wed, 6 Mar 1996, Theodore Ts'o wrote:

> I'm the most uncomfortable with the changes to the bootsector. We only
> have so many configuration bytes available, and using a full byte for
> the blind option seems to not be the best use of that resource.
>
> Question: is it really critical that all of the hardware probe messages
> always be accessible via the blind-mode console? How about this as a
> proposal:
>
> All kernels will have support for turning on/off "blind mode" via the
> escape sequences. Init will recognize the kernel command line argument
> "blind=1", and if it sees it, it will send the escape sequence to all of
> the console. A blind person who wishes to see the boot messages gets
> Linux running using the above procedure, and then recompiles a kernel
> whose default mode is "blind mode on". That will allow the blind person
> to see the hardware probing boot messages.
>
> That simplifies the changes to the kernel, and hopefully it meets your
> requirements. What do you think?

I've thought through the various permutations, believe me: yes, your idea
works much better then most, but it requires a custom (or at least recent)
init and it doesn't give any help if the boot locks up before getting to
init.

I agree that using another bytes of the bootsector is disagreeable, but I
don't see any other way of pulling the information from the vidmode setting,
and that vidmode setting is by far the easiest thing to change in a kernel.
(Indeed, I spent a long hard search trying to figure out why it wasn't being
propegated through in the first place.)

For now, only a single bit of the flag in the boot sector is really being
used. Perhaps the remaining 15 (sorry, but it was implemented as a word, not
a byte) could be left open as additional flags?

Also, that patch only uses 0x1F0 on the i386. Other architectures (for good
or for bad) haven't been touched.

I suppose a bit in the current screen_info structure could be used, if one
can be spared somewhere. The highest bit of video_page, perhaps.

> - Ted

--
Kenneth Albanowski (kjahds@kjahds.com, CIS: 70705,126)




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