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Message-ID: <0e1d7a917332b90666417ac0508f8a6d@mailhost.ics.forth.gr>
Date: Tue, 16 Jun 2020 14:51:53 +0300
From: Nick Kossifidis <mick@....forth.gr>
To: Zong Li <zong.li@...ive.com>
Cc: paul.walmsley@...ive.com, palmer@...belt.com,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] riscv: Register System RAM as iomem resources
Στις 2020-06-16 10:45, Zong Li έγραψε:
> Add System RAM to /proc/iomem, various tools expect it such as kdump.
> It is also needed for page_is_ram API which checks the specified
> address
> whether registered as System RAM in iomem_resource list.
>
> Signed-off-by: Zong Li <zong.li@...ive.com>
> ---
> arch/riscv/mm/init.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index f4adb3684f3d..bbe816e03b2f 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -517,6 +517,27 @@ void mark_rodata_ro(void)
> }
> #endif
>
> +void __init resource_init(void)
> +{
> + struct memblock_region *region;
> +
> + for_each_memblock(memory, region) {
> + struct resource *res;
> +
> + res = memblock_alloc(sizeof(struct resource), SMP_CACHE_BYTES);
> + if (!res)
> + panic("%s: Failed to allocate %zu bytes\n", __func__,
> + sizeof(struct resource));
> +
> + res->name = "System RAM";
> + res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
> + res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) -
> 1;
> + res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> +
> + request_resource(&iomem_resource, res);
> + }
> +}
> +
> void __init paging_init(void)
> {
> setup_vm_final();
> @@ -524,6 +545,7 @@ void __init paging_init(void)
> sparse_init();
> setup_zero_page();
> zone_sizes_init();
> + resource_init();
> }
>
> #ifdef CONFIG_SPARSEMEM_VMEMMAP
I already have a patch for registering System RAM as an iomem resource
on my kexec/kdump series. Since I don't care about System RAM regions
being accurately exposed to userspace (I parse the current device tree
instead) I just use memblock_start_of_DRAM/end_of_DRAM. This approach
from arm64 codebase is better since it also handles the case of sparse
memory regions but in order to be useful for kdump we need to add the
various segments of the kernel image as child nodes to their respective
region for kexec-tools. I'll re-spin my patchset anyway so I'll extend
it to better handle System RAM regions.
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