Re: Custom boot loader stub

On Fri, 24 Oct 2025 14:30:17 +0300
Valery Ushakov <[email protected]> wrote:

> From a quick look I'd venture a guess that you might want to use
> poll-tty first, before calling read to read the data that you now know
> is there.
> 
> -uwe

Thanks for the pointers. I've just realised the solution was right
there in front of me in Illumos prom_getchar(). My brain didn't quite
register that it was polling for input in a while loop.

This is what I should have done:

char ofw_read_stdin_char(void)
{
	int64_t i64;
	char    c;

	do
	{
		/* Continually returns -2 while no data is ready on stdin */
		i64 = ofw_read_stdin(&c, 1);
	} while (i64 == -2);

	ASSERT(i64 == 1); /* Catch -1 on read error */
	return c;
}

Now everything is working correctly:

Running SPARC-V9 bootblk

ihandle_stdin  0xFEB51F90
ihandle_stdout 0xFEB51D88
Press Enter to exit: 
Program terminated
{0} ok