On Sat, Apr 02, 2016 at 01:13:37PM -0700, Andy Lutomirski wrote:
> Given that I this isn't really a regression with my patches (it
> probably never worked much better on 32-bit and the regs never would
> have shown at all on 64-bit),
You're right. That thing calls printk *and* early_printk, WTF:
#ifdef CONFIG_EARLY_PRINTK
call early_printk
...
call dump_stack
...
call __print_symbol
those last two call printk. Great.
> I propose a different approach: make
> printk work earlier. Something like:
>
> if (early) {
> early_printk(args);
> }
>
> or early_vprintk or whatever.
>
> If the cost of a branch mattered, this could be alternative-patched
> out later on, but that seems silly. I also bet that a more sensible
> fallback could be created in which printk would try to use an early
> console if there's no real console.
So how about this:
printk() does
vprintk_func = this_cpu_read(printk_func);
and that's
DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default
I guess we can make that function be early_printk-something and once
printk is initialized, we overwrite it with vprintk_default.
Elegant and no need for if branches and alternatives.
Hmmm.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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