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From:   Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Date:   Sat, 3 Apr 2021 19:02:13 -0700
Message-ID: <CALCv0x3sGY8t_NCch7qa6KijoxwvFJJYQEZB5kOMuK35C=c3og@mail.gmail.com>
Subject: Re: [PATCH] MIPS: fix memory reservation for non-usermem setups
To:     Mike Rapoport <rppt@kernel.org>
Cc:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Tiezhu Yang <yangtiezhu@loongson.cn>,
        Jinyang He <hejinyang@loongson.cn>,
        Youling Tang <tangyouling@loongson.cn>,
        Tobias Wolf <dev-NTEO@vplace.de>,
        Marcin Nowakowski <marcin.nowakowski@mips.com>,
        linux-mips@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        stable@vger.kernel.org
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Hi Mike,

On Tue, Mar 16, 2021 at 11:33 PM Mike Rapoport <rppt@kernel.org> wrote:
>
> Hi Ilya,
>
> On Tue, Mar 16, 2021 at 10:10:09PM -0700, Ilya Lipnitskiy wrote:
> > Hi Thomas,
> >
> > On Fri, Mar 12, 2021 at 7:19 AM Thomas Bogendoerfer
> > <tsbogend@alpha.franken.de> wrote:
> > >
> > > On Sun, Mar 07, 2021 at 11:40:30AM -0800, Ilya Lipnitskiy wrote:
> > > > From: Tobias Wolf <dev-NTEO@vplace.de>
> > > >
> > > > Commit 67a3ba25aa95 ("MIPS: Fix incorrect mem=X@Y handling") introduced a new
> > > > issue for rt288x where "PHYS_OFFSET" is 0x0 but the calculated "ramstart" is
> > > > not. As the prerequisite of custom memory map has been removed, this results
> > > > in the full memory range of 0x0 - 0x8000000 to be marked as reserved for this
> > > > platform.
> > >
> > > and where is the problem here ?
> > Turns out this was already attempted to be upstreamed - not clear why
> > it wasn't merged. Context:
> > https://lore.kernel.org/linux-mips/6504517.U6H5IhoIOn@loki/
> >
> > I hope the thread above helps you understand the problem.
>
> The memory initialization was a bit different then. Do you still see the
> same problem?
Thanks for asking. I obtained a RT2880 device and gave it a try. It
hangs at boot without this patch, however selecting
MIPS_AUTO_PFN_OFFSET fixes it. Also, no more messages like "Wasting
1048576 bytes for tracking 32768 unused pages". MIPS_AUTO_PFN_OFFSET
was suggested by Paul Burton here:
https://lore.kernel.org/linux-mips/20180820233111.xww5232dxbuouf4n@pburton-laptop/

I will supersede this patch with one that simply selects
MIPS_AUTO_PFN_OFFSET for this SOC.

Ilya