From: Anup Patel <anup@brainfault.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Palmer Dabbelt <palmer@sifive.com>,
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>,
Albert Ou <aou@eecs.berkeley.edu>,
Paul Walmsley <paul.walmsley@sifive.com>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>
Subject: Re: [PATCH v4 2/2] RISC-V: Setup initial page tables in two stages
Date: Tue, 21 May 2019 13:08:14 +0530 [thread overview]
Message-ID: <CAAhSdy2SRxMEaJE6WsP87KeXw_J1X-6eYAMV7j0bhEGgNcLiyg@mail.gmail.com> (raw)
In-Reply-To: <20190520114352.GA5372@infradead.org>
On Mon, May 20, 2019 at 5:13 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> > void __init parse_dtb(unsigned int hartid, void *dtb)
> > {
> > - if (early_init_dt_scan(__va(dtb)))
> > + dtb = (void *)fix_to_virt(FIX_FDT) + ((uintptr_t)dtb & ~PAGE_MASK);
> > + if (early_init_dt_scan(dtb))
>
> FYI, parse_dtb in mainline now lost the hartid argument and takes a
> phys_addr_t for the dtb address.
Okay, this patch is based on 5.1 kernel. I guess I will have to rebase
it anyway.
>
> That being said I find the above way to magic. So we take the fixmap
> address and then only the offset from something passed as a pointer?
> This just looks very weird. The way FIX_FDT is defined to add to my
> confusion, which might partially be due to not understanding fixmaps
> very well. But it seems like at very least we should set up an
> actual kernel pointer for the dtb in setup_vm based on what that
> gets passed and stop passing any arguments to parse_dtb to keep
> that magic in one place. And possibly add some comment.
I agree with your suggestion. I will setup early_dtb_ptr in setup_vm()
and use it here.
FYI, the fixmap virtual address range is not covered by linear va-to-pa
translation (i.e. __va() and __pa() cannot be used). The mapping
granularity of fixmap is always PAGE_SIZE hence add offset to
fix_to_virt(FIX_FDT).
>
> > +#if MAX_EARLY_MAPPING_SIZE < PGDIR_SIZE
>
> It seems MAX_EARLY_MAPPING_SIZE is defined to a fix constant,
> why do we need these conditionals?
Sure, I will remove the conditional. It's totally redundant. I forgot to
remove it previously.
Regards,
Anup
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2019-05-21 7:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-02 5:02 [PATCH v4 0/2] Two-stagged initial page table setup Anup Patel
2019-05-02 5:02 ` [PATCH v4 1/2] RISC-V: Fix memory reservation in setup_bootmem() Anup Patel
2019-05-02 5:02 ` [PATCH v4 2/2] RISC-V: Setup initial page tables in two stages Anup Patel
2019-05-20 11:43 ` Christoph Hellwig
2019-05-21 7:38 ` Anup Patel [this message]
2019-05-20 8:44 ` [PATCH v4 0/2] Two-stagged initial page table setup Anup Patel
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=CAAhSdy2SRxMEaJE6WsP87KeXw_J1X-6eYAMV7j0bhEGgNcLiyg@mail.gmail.com \
--to=anup@brainfault.org \
--cc=Anup.Patel@wdc.com \
--cc=Atish.Patra@wdc.com \
--cc=aou@eecs.berkeley.edu \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=palmer@sifive.com \
--cc=paul.walmsley@sifive.com \
--cc=rppt@linux.ibm.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).