> > 
> > That doesn't seem to explain even a quiet boot up taking several times
> > longer than 4.19, and package installation over an ethernet connection
> > (thus not using the console) also taking several times longer.
> 
> Maybe it's a slow disk?
> 
> ATA (libata) CS5536 driver is having issues with spurious IRQs and often
> disables IRQs completely during the boot. You should see a warning
> in dmesg. This was the reason for slowness on my FuLoong mini-PC. A
> workaround is to switch to old IDE driver.
> 
> Discussion: https://lore.kernel.org/linux-mips/20190106124607.GK27785@darkstar.musicnaut.iki.fi/
> 
> A.

I find that this problem is odd. I've been using libata personally since 2014 and
never had any IRQ problem at all. How can the problem even occur at all? Perhaps
related to a rarely used kernel option that trigger it, or a bug in the PMON boot
firmware? I don't know...

But I think some versions of the PMON boot firmware have odd bugs. I'm currently
using the PMON firmware built by an OpenBSD developer, but I cannot find the link
anymore.

Tom Li