On Thu, Jul 28, 2016 at 11:59:20AM +0200, Max Staudt wrote:

On 07/27/2016 03:33 PM, Theodore Ts'o wrote:

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On Wed, Jul 27, 2016 at 02:14:24PM +0200, Max Staudt wrote:

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If you set the IRQ to 0 it should poll anyway (0 means 'no IRQ') so I
don't think the option is needed. At least it seems sufficient to get me
by when I meet buggy PC BIOSes and the like

That's exactly what the patch does - but if there is already a way to set the
IRQ to 0, I would of course prefer to use that.

It seems I haven't found the trick you're using - could you please tell me how
you set the IRQ to 0?  I can't change it in the BIOS, so I have to do it at
the kernel level at the latest.

So the problem is that you can't use setserial because you want to use
this port for your console?  And so you don't want to set it in an initscript?

Exactly. There is no initscript when I use rdinit=/bin/bash, so I have no choice
but to set it in the kernel. As soon as /bin/bash accesses /dev/ttyS0, the
console hangs.

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The one thing which is really unfortunate with this patch is that it's
a global, so it forces polling for *all* serial ports.  And it may be
that it's only base ports on the motherboard which needs this hack.

I agree, and I thought about it, but since this is meant for a very limited
audience, I think a catch-all is the easiest solution - both in terms of
implementation as well as ease of use.

It's not meant for general consumption anyway.

Then I really don't want to have to maintain and support such a kernel
option for 20+ years, just because of one broken system out there like
this.  There are workarounds for this, as you have seen, including
booting with a "real" userspace, so I don't want to take this patch.

thanks,

greg k-h