linux-kernel - Re: [PATCH] ARM: mmu: fix access to illegal address when using earlycon & memblock=debug

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Date:   Wed, 31 Aug 2022 14:51:07 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     Victor Hassan <victor@...winnertech.com>, linus.walleij@...aro.org,
        yanfei.xu@...driver.com, ardb@...nel.org, tglx@...utronix.de,
        mirq-linux@...e.qmqm.pl, arnd@...db.de,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        allwinner-opensource-support@...winnertech.com
Subject: Re: [PATCH] ARM: mmu: fix access to illegal address when using
 earlycon & memblock=debug

On Wed, Aug 31, 2022 at 01:52:57PM +0200, Marek Szyprowski wrote:
> Hi Victor,
> 
> On 16.03.2022 03:33, Victor Hassan wrote:
> > earlycon uses fixmap to create a memory map,
> > So we need to close earlycon before closing fixmap,
> > otherwise printk will access illegal addresses.
> > After creating a new memory map, we open earlycon again.
> >
> > Signed-off-by: Victor Hassan <victor@...winnertech.com>
> 
> This patch landed in linux next-20220831 as commit a76886d117cb ("ARM: 
> 9223/1: mmu: fix access to illegal address when using earlycon & 
> memblock=debug"). Unfortunately it breaks booting of all my test boards 
> which *do not* use earlycon. It can be easily reproduced even with QEMU.
> 
> With kernel compiled from multi_v7_defconfig the following setup boots:
> 
> $ qemu-system-arm -nographic -kernel arch/arm/boot/zImage -append 
> "console=ttyAMA0 earlycon" -M virt -smp 2 -m 512
> 
> while this one doesn't:
> 
> $ qemu-system-arm -nographic -kernel arch/arm/boot/zImage -append 
> "console=ttyAMA0" -M virt -smp 2 -m 512

That's the second patch to drop from my merge yesterday... not good.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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