linux-kernel - Re: Trying to kexec on Allwinner A80

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Date:   Tue, 7 Apr 2020 10:01:44 +0200
From:   Corentin Labbe <clabbe.montjoie@...il.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     ebiederm@...ssion.com, kexec@...ts.infradead.org, wens@...e.org,
        linux-arm-kernel@...ts.infradead.org, mripard@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Trying to kexec on Allwinner A80

On Tue, Apr 07, 2020 at 08:31:17AM +0100, Russell King - ARM Linux admin wrote:
> On Mon, Apr 06, 2020 at 10:10:53PM +0200, Corentin Labbe wrote:
> > On Mon, Apr 06, 2020 at 10:37:29AM +0100, Russell King - ARM Linux admin wrote:
> > > On Mon, Apr 06, 2020 at 11:25:40AM +0200, Corentin Labbe wrote:
> > > > On Mon, Apr 06, 2020 at 10:16:00AM +0100, Russell King - ARM Linux admin wrote:
> > > > > On Mon, Apr 06, 2020 at 10:27:20AM +0200, Corentin Labbe wrote:
> > > > > > Hello
> > > > > > 
> > > > > > I am trying to add the last missing Allwinner Soc in kernelci: the A80.
> > > > > > But this SoC does not have any way to be used in kernelci, no USB nor network in uboot.
> > > > > > So I have tried to fake uboot since the kernel has network support and run the new kernel via kexec.
> > > > > > 
> > > > > > But kexec 2.0.18 fail to work:
> > > > > > kexec --force /tmp/kernel --initrd /tmp/ramdisk --dtb /tmp/dtb --command-line='console=ttyS0,115200n8 root=/dev/ram0 earlycon=uart,mmio32,0x7000000 ip=dhcp'
> > > > > 
> > > > > What happens if you omit the dtb argument?
> > > > > 
> > > > 
> > > > No change without dtb
> > > > 
> > > > I have also tried to add --mem-mim and --mem-max without any change.
> > > > I given mem according to what I saw in /proc/iomem
> > > > 20000000-9fffffff : System RAM
> > > >   20008000-207fffff : Kernel code
> > > >   20900000-209a0c87 : Kernel data
> > > > So I gave --mem-min 0x30000000 --mem-max 0x9fffffff
> > > > Anyway, the result is always the same.
> > > 
> > > The next step is to enable the early debugging - first in the
> > > decompressor - add #define DEBUG to the top of
> > > arch/arm/boot/compressed/head.S
> > > 
> > > Also enable DEBUG_LL in the kernel and use earlyprintk to see if you can
> > > get anything from the new kernel.
> > > 
> > 
> > I dont know what happened, but now I always get "Could not find a free area of memory of 0x86c1c0 bytes..." (even with kexec 2.0.18)
> > Furthermore, I have added crashkernel=128M to the cmdlist
> > I have verified that the reservation is working:
> > 20000000-9fffffff : System RAM
> >   20008000-207fffff : Kernel code
> >   20900000-209a0c87 : Kernel data
> >   40000000-47ffffff : Crash kernel
> > But even with this reservation, no change.
> 
> crashkernel is only necessary if you're loading a kenrel image to be
> booted when the existing one has crashed. For the problem you're
> seeing, it's an unnecessary additional change; please drop that.
> 
> You could try running kexec with debug enabled to see more information.
> 

I am already running with --debug