Messages in this thread | | | Subject | Re: [PATCH 1/3] riscv: Fix memory_limit for 64-bit kernel | From | Kefeng Wang <> | Date | Thu, 1 Jul 2021 18:44:37 +0800 |
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On 2021/6/29 17:13, Alexandre Ghiti wrote: > As described in Documentation/riscv/vm-layout.rst, the end of the > virtual address space for 64-bit kernel is occupied by the modules/BPF/ > kernel mappings so this actually reduces the amount of memory we are able > to map and then use in the linear mapping. So make sure this limit is > correctly set. > > Fixes: c9811e379b21 ("riscv: Add mem kernel parameter support")
Should the Fixes tag be de043da0b9e7 (“RISC-V: Fix usage of memblock_enforce_memory_limit“),
The -PAGE_OFFSET is set to the maximal physical memory from this point :)
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> > --- > arch/riscv/mm/init.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 12f956b3a674..04a5db3a9788 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -124,10 +124,17 @@ void __init mem_init(void) > } > > /* > - * The default maximal physical memory size is -PAGE_OFFSET, > - * limit the memory size via mem. > + * The default maximal physical memory size is -PAGE_OFFSET for 32-bit kernel, > + * whereas for 64-bit kernel, the end of the virtual address space is occupied > + * by the modules/BPF/kernel mappings which reduces the available size of the > + * linear mapping. > + * Limit the memory size via mem. > */ > +#ifdef CONFIG_64BIT > +static phys_addr_t memory_limit = -PAGE_OFFSET - SZ_4G; > +#else > static phys_addr_t memory_limit = -PAGE_OFFSET; > +#endif > > static int __init early_mem(char *p) > {
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