From: Atish Patra <atishp@atishpatra.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Mark Rutland <mark.rutland@arm.com>,
linux-efi <linux-efi@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
Heinrich Schuchardt <xypron.glpk@gmx.de>,
Masahiro Yamada <masahiroy@kernel.org>,
Anup Patel <anup.patel@wdc.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Mike Rapoport <rppt@linux.ibm.com>,
Atish Patra <atish.patra@wdc.com>,
Palmer Dabbelt <palmer@dabbelt.com>, Zong Li <zong.li@sifive.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Greentime Hu <greentime.hu@sifive.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFT PATCH v3 1/9] RISC-V: Move DT mapping outof fixmap
Date: Mon, 20 Jul 2020 21:18:21 -0700 [thread overview]
Message-ID: <CAOnJCUL2X9mK41iHLCg1_rtj7JS4p41hqXfmd=hyxK=2t5QQog@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a3iUdoOZrORz+aeXYiO35Lp8snrCkxSUPAY6Fh2EinaOw@mail.gmail.com>
On Sat, Jul 18, 2020 at 2:24 AM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Sat, Jul 18, 2020 at 3:05 AM Atish Patra <atishp@atishpatra.org> wrote:
> > On Thu, Jul 16, 2020 at 11:32 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > > On Fri, Jul 17, 2020 at 1:41 AM Atish Patra <atish.patra@wdc.com> wrote:
> > > > +#define DTB_EARLY_SIZE SZ_1M
> > > > +static char early_dtb[DTB_EARLY_SIZE] __initdata;
> > >
> > > Hardcoding the size in .bss seems slightly problematic both for
> > > small and for big systems. On machines with very little memory,
> > > this can lead to running out of free pages before .initdata gets freed,
> > > and it increases the size of the uncompressed vmlinux file by quite
> > > a bit.
> > >
> > > On some systems, the 1MB limit may get too small. While most dtbs
> > > would fall into the range between 10KB and 100KB, it can also be
> > > much larger than that, e.g. when there are DT properties that include
> > > blobs like device firmware that gets loaded into hardware by a kernel
> > > driver.
> > >
> > I was not aware that we can do such things. Is there a current example of that ?
>
> I worked on a product in the distant past where the host firmware
> included the ethernet controller firmware as a DT property[1] to get around
> restrictions on redistributing the blob in the linux-firmware package.
>
> For the .dts files we distribute with the kernel, that would not make
> sense, and I don't know of any current machines that do this in their
> system firmware.
>
> > > Is there anything stopping you from parsing the FDT in its original
> > > location without the extra copy before it gets unflattened?
> >
> > That's what the original code was doing. A fixmap entry was added to
> > map the original fdt
> > location to a virtual so that parse_dtb can be operated on a virtual
> > address. But we can't map
> > both FDT & early ioremap within a single PMD region( 2MB ). That's why
> > we removed the DT
> > mapping from the fixmap to .bss section. The other alternate option is
> > to increase the fixmap space to 4MB which seems more fragile.
>
> Could the original location just be part of the regular linear mapping of all
> RAM?
No. Because we don't map the entire RAM until setup_vm_final().
We need to parse DT before setup_vm_final() to get the memblocks and
reserved memory regions.
I'm not too familiar with the early mapping code myself, so it may not
> be possible, but that would be the most logical place where I'd put it.
>
> Arnd
>
> [1] drivers/net/ethernet/toshiba/spider_net.c
--
Regards,
Atish
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2020-07-21 4:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 23:40 [RFT PATCH v3 0/9] Add UEFI support for RISC-V Atish Patra
2020-07-16 23:40 ` [RFT PATCH v3 1/9] RISC-V: Move DT mapping outof fixmap Atish Patra
2020-07-17 6:32 ` Arnd Bergmann
2020-07-18 1:05 ` Atish Patra
2020-07-18 9:24 ` Arnd Bergmann
2020-07-21 4:18 ` Atish Patra [this message]
2020-07-21 8:57 ` Arnd Bergmann
2020-07-21 9:02 ` Ard Biesheuvel
2020-07-21 9:30 ` Anup Patel
2020-07-16 23:40 ` [RFT PATCH v3 2/9] RISC-V: Add early ioremap support Atish Patra
2020-07-16 23:40 ` [RFT PATCH v3 3/9] RISC-V: Implement late mapping page table allocation functions Atish Patra
2020-07-16 23:40 ` [RFT PATCH v3 4/9] include: pe.h: Add RISC-V related PE definition Atish Patra
2020-07-16 23:41 ` [RFT PATCH v3 5/9] RISC-V: Add PE/COFF header for EFI stub Atish Patra
2020-07-16 23:41 ` [RFT PATCH v3 6/9] RISC-V: Add EFI stub support Atish Patra
2020-07-16 23:41 ` [RFT PATCH v3 7/9] efi: Rename arm-init to efi-init common for all arch Atish Patra
2020-07-16 23:41 ` [RFT PATCH v3 8/9] RISC-V: Add EFI runtime services Atish Patra
2020-07-16 23:41 ` [RFT PATCH v3 9/9] RISC-V: Add page table dump support for uefi Atish Patra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAOnJCUL2X9mK41iHLCg1_rtj7JS4p41hqXfmd=hyxK=2t5QQog@mail.gmail.com' \
--to=atishp@atishpatra.org \
--cc=anup.patel@wdc.com \
--cc=ardb@kernel.org \
--cc=arnd@arndb.de \
--cc=atish.patra@wdc.com \
--cc=greentime.hu@sifive.com \
--cc=keescook@chromium.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-efi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=masahiroy@kernel.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=rppt@linux.ibm.com \
--cc=will@kernel.org \
--cc=xypron.glpk@gmx.de \
--cc=zong.li@sifive.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).