From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Mike Rapoport <rppt@kernel.org>
Cc: Rob Herring <robh@kernel.org>,
Russell King <linux@armlinux.org.uk>,
Nicolas Pitre <nico@fluxnic.net>,
Ard Biesheuvel <ardb@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Nick Kossifidis <mick@ics.forth.gr>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Frank Rowand <frowand.list@gmail.com>,
Dave Young <dyoung@redhat.com>, Baoquan He <bhe@redhat.com>,
Vivek Goyal <vgoyal@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-riscv <linux-riscv@lists.infradead.org>,
kexec@lists.infradead.org, Linux MM <linux-mm@kvack.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 02/10] memblock: Add variables for usable memory limitation
Date: Mon, 19 Jul 2021 08:59:03 +0200 [thread overview]
Message-ID: <CAMuHMdXfFhzm48U2Hvjz8yrjPsQbagW4aC_L-QE_Q6yx1Lo=tA@mail.gmail.com> (raw)
In-Reply-To: <YPP06QG7hfypZgYg@kernel.org>
Hi Mike,
On Sun, Jul 18, 2021 at 11:31 AM Mike Rapoport <rppt@kernel.org> wrote:
> On Wed, Jul 14, 2021 at 07:51:01AM -0600, Rob Herring wrote:
> > On Wed, Jul 14, 2021 at 02:50:12PM +0200, Geert Uytterhoeven wrote:
> > > Add two global variables (cap_mem_addr and cap_mem_size) for storing a
> > > base address and size, describing a limited region in which memory may
> > > be considered available for use by the kernel. If enabled, memory
> > > outside of this range is not available for use.
> > >
> > > These variables can by filled by firmware-specific code, and used in
> > > calls to memblock_cap_memory_range() by architecture-specific code.
> > > An example user is the parser of the "linux,usable-memory-range"
> > > property in the DT "/chosen" node.
> > >
> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > ---
> > > This is similar to how the initial ramdisk (phys_initrd_{start,size})
> > > and ELF core headers (elfcorehdr_{addr,size})) are handled.
> > >
> > > Does there exist a suitable place in the common memblock code to call
> > > "memblock_cap_memory_range(cap_mem_addr, cap_mem_size)", or does this
> > > have to be done in architecture-specific code?
> >
> > Can't you just call it from early_init_dt_scan_usablemem? If the
> > property is present, you want to call it. If the property is not
> > present, nothing happens.
I will have a look...
> For memblock_cap_memory_range() to work properly it should be called after
> memory is detected and added to memblock with memblock_add[_node]()
>
> I'm not huge fan of adding more globals to memblock so if such ordering can
> be implemented on the DT side it would be great.
Me neither ;-)
> I don't see a way to actually enforce this ordering, so maybe we'd want to
> add warning in memblock_cap_memory_range() if memblock.memory is empty.
"linux,usable-memory-range" is optional, and typically used only in
crashdump kernels, so it would be a bad idea to add such a warning.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2021-07-19 6:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 12:50 [PATCH v4 00/10] Add generic support for kdump DT properties Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 01/10] crash_dump: Make elfcorehdr_{addr,size} always visible Geert Uytterhoeven
2021-07-14 13:46 ` Rob Herring
2021-07-14 12:50 ` [PATCH v4 02/10] memblock: Add variables for usable memory limitation Geert Uytterhoeven
2021-07-14 13:51 ` Rob Herring
2021-07-18 9:31 ` Mike Rapoport
2021-07-19 6:59 ` Geert Uytterhoeven [this message]
2021-07-20 5:41 ` Mike Rapoport
2021-07-20 7:23 ` Geert Uytterhoeven
2021-08-11 8:11 ` Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 03/10] of: fdt: Add generic support for parsing elf core headers property Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 04/10] of: fdt: Add generic support for parsing usable memory range property Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 05/10] of: fdt: Use IS_ENABLED(CONFIG_BLK_DEV_INITRD) instead of #ifdef Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 06/10] riscv: Remove non-standard linux,elfcorehdr handling Geert Uytterhoeven
2021-07-20 15:43 ` Palmer Dabbelt
2021-07-23 15:17 ` Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 07/10] arm64: kdump: Remove custom linux,elfcorehdr parsing Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 08/10] arm64: kdump: Remove custom linux,usable-memory-range parsing Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 09/10] arm64: kdump: Use IS_ENABLED(CONFIG_CRASH_DUMP) instead of #ifdef Geert Uytterhoeven
2021-07-14 12:50 ` [PATCH v4 10/10] ARM: Parse kdump DT properties Geert Uytterhoeven
2021-07-14 14:53 ` Rob Herring
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