RE: kernel boot fail with efi earlyprintk (bisected)

[Zheng, Lv]

Hi,

> From: Dave Young [mailto:dyoung@xxxxxxxxxx]
> Sent: Monday, August 25, 2014 2:07 PM
> To: Matt Fleming
> Cc: Zheng, Lv; Fleming, Matt; linux-efi@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx;
> lenb@xxxxxxxxxx; Wysocki, Rafael J; Moore, Robert
> Subject: Re: kernel boot fail with efi earlyprintk (bisected)
> 
> On 08/22/14 at 06:02pm, Dave Young wrote:
> > On 08/21/14 at 09:52pm, Matt Fleming wrote:
> > > On Tue, 19 Aug, at 04:16:58PM, Dave Young wrote:
> > > > Hi,
> > > >
> > > > 3.16 kernel boot fail with earlyprintk=efi on my laptop.
> > > > It keeps scrolling at the bottom line of screen.
> > > >
> > > > Bisected, the first bad commit is below:
> > > > commit 86dfc6f339886559d80ee0d4bd20fe5ee90450f0
> > > > Author: Lv Zheng <lv.zheng@xxxxxxxxx>
> > > > Date:   Fri Apr 4 12:38:57 2014 +0800
> > > >
> > > >     ACPICA: Tables: Fix table checksums verification before installation.
> > > >
> > > >
> > > > I did some debugging by enabling both serial and efi earlyprintk, below is
> > > > some debug dmesg, seems early_ioremap fails in scroll up function due to
> > > > no free slot, but I'm still not sure if the debug info is right or not.
> > >
> > > Thanks Dave, your callstack seems to make sense.
> > >
> > > Can you also enable early_ioremap_debug so that we can figure out where
> > > all the FIXMAP slots are going?
> >
> > With early_ioremap_debug enabled, there will be a lot of "dropped printk", so
> > I can not get any useful information.
> >
> > Will try to do more debug.
> 
> early_ioremap_debug does not work because we are debugging early_printk but
> early_ioremap_debug itself will print warning message at the same time.
> 
> Tried what Lv mentioned, increasing the early ioremap slots does help.

Could you send a tested patch to linux-acpi@xxxxxxxxxxxxxxx for this?
I think the number of early mapping slots need to be increased by 1 because of this case.

Thanks and best regards
-Lv
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