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

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Date:   Thu, 1 Sep 2022 08:49:19 -0500
From:   Rob Herring <robh@...nel.org>
To:     Victor Hassan <victor@...winnertech.com>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Russell King <linux@...linux.org.uk>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Linus Walleij <linus.walleij@...aro.org>,
        yanfei.xu@...driver.com, Ard Biesheuvel <ardb@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: mmu: fix access to illegal address when using
 earlycon & memblock=debug

On Thu, Sep 1, 2022 at 8:21 AM Rob Herring <robh@...nel.org> wrote:
>
> On Thu, Sep 1, 2022 at 7:54 AM Victor Hassan <victor@...winnertech.com> wrote:
> >
> >
> >
> > On 2022/8/31 20:37, Victor Hassan wrote:
> > > On 8/31/2022 7:52 PM, 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.
>
> How? Due to recent changes in how printk and the consoles work or just
> because create_mapping() can print? In the latter case, the only
> variable input is the phys address. I think most if not all prints
> cannot occur.

Ah, I missed the memblock debug part on the subject...

Rob