linux-kernel - Re: [PATCH 4/7] RISC-V: Update page tables to cover the whole linear mapping

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Date:   Thu, 28 Mar 2019 12:24:31 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Anup Patel <anup@...infault.org>
Cc:     Albert Ou <aou@...s.berkeley.edu>,
        Palmer Dabbelt <palmer@...ive.com>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        Stephen Bates <sbates@...thlin.com>,
        Atish Patra <atish.patra@....com>,
        Anup Patel <anup.patel@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-riscv@...ts.infradead.org,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Christoph Hellwig <hch@....de>, Zong Li <zongbox@...il.com>
Subject: Re: [PATCH 4/7] RISC-V: Update page tables to cover the whole linear
 mapping



On 2019-03-28 4:03 a.m., Anup Patel wrote:
> I understand that this patch is inline with your virtual memory layout cleanup
> but the way we map virtual memory in swapper_pg_dir is bound to change.
> 
> We should not be mapping complete virtual memory in swapper_pd_dir()
> rather we should only map based on amount of RAM available.
> 
> Refer, https://www.lkml.org/lkml/2019/3/24/3
> 
> The setup_vm() should only map vmlinux_start to vmlinux_end plus the
> FDT. Complete virtual memory mapping should be done after we have
> done early parsing of FDT when we know available memory banks in
> setup_vm_final() (called from paging_init())

That makes sense, but I think a lot of it sounds a out of the scope of
what I'm doing in this patch set.

I could attempt to update my patchset so instead of expanding the linear
region on boot, we add the page tables in arch_add_memory. That would
make more sense when considering the direction you want to head with
setup_vm.

Logan