On Monday 23 April 2012 17:17:57 Wolfgang Denk wrote: > Mike Frysinger wrote: > > also, what you're proposing is changing the behavior of u-boot when it's > > in the sandbox so that it acts less like the hardware. when you run > > u-boot on the hardware and it's sitting at the prompt, u-boot is running > > the cpu at 100%. > > Correct. But then U-Boot is the only master of the CPU, and nothing > else can be run in parallel. > > In the sandbox, U-Boot is an ordinary user space application and as > such is supposed to behave well. Burning 100% CPU is a polling input > loop is about the most stupid thing we can do.
not when you're aiming to act like the hardware whenever possible. we
specifically do not want #ifdef CONFIG_SANDBOX outside of sandbox-specific
drivers if we can avoid it. that means we are bound by the implicit
constraints at the driver boundaries. so if u-boot common code does:
while (tstc())
...
then sandbox should be eating the cpu. however, it seems that the hush shell
does while (getc()), so that shouldn't be an issue here.
> > > Why invent new methods when we can encapsulate this in the input
> > > interface?
> >
> > i'm not inventing new methods. i'm telling you that the sandbox OS layer
> > today cannot access the C library's errno because u-boot's own
> > implementation of errno is overriding it. so any call sandbox makes to
> > the OS (like read() or select() or poll()) that results in an error,
> > sandbox has no way of knowing the underlying reason.
>
> Than this needs to be fixed for sandbox?
the only way to fix it is what i suggested: rename "int errno" in lib/errno.c
to something like "int uboot_errno" and then add to errno.h: "#define errno
uboot_errno". this shouldn't make any difference at all to compiled code. the
only difference is that people doing symbol debugging would get a different
symbol name.
-mike
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