Dear Mike Frysinger,
In message <201204231503.08835.vap...@gentoo.org> you wrote:
>
> > I don't see why we cannot simply read from stdin (or rathr from file
> > descriptor 0) as usual?
>
> the "usual" method of reading from stdin involves the tty doing buffering and
> the application only seeing fully flushed lines. thus it would not operate
> the
That's why I wrote "or rather from fd 0".
> same as the hardware (where u-boot gets every char as you type) and you
> wouldn't be able to handle things like tab completion.
C'me on. That's a standard issue. We know how to handle this, right?
> > You can use standard methods like select() or poll() to wait for input,
> > which will also inform you about events like EOF.
>
> because that isn't how u-boot on the hardware works. u-boot itself calls
> tstc() to see if there's any data and does so in a continuous loop. when
> there is data, it calls getc(). tstc() should not block, and getc() isn't>
> call unless u-boot knows there's data.
That's why I suggested to use select() or poll() to poll for available
characters, just like the hardware does. Only we do NOT want to tun
this in a tight loop. We will most likely want to add a sufficiently
large delay to keep CPU load in reasonable bounds.
> it is also problematic (currently) to get access to errno from the C library
> because u-boot itself has a variable called "errno". so we cannot call the C
Why invent new methods when we can encapsulate this in the input
interface?
We do not even have to pass EOF on to higher layers in U-Boot - we
could exit directly in the tty interface code.
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
As usual, this being a 1.3.x release, I haven't even compiled this
kernel yet. So if it works, you should be doubly impressed.
- Linus Torvalds in <199506181536.saa10...@keos.cs.helsinki.fi>
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