Re: [PATCH v2 2/2] x86: reimplement mem boot option

[Wen Congyang <wency@cn.fujitsu.com>]

Hi, H. Peter Anvin

Do you have time to review this patch?

Thanks
Wen Congyang

At 08/21/2012 04:11 PM, Wen Congyang Wrote:
> Current mem boot option only can work for non efi environment. If the user
> specifies add_efi_memmap, it cannot work for efi environment. In
> the efi environment, we call e820_add_region() to add the memory map. So
> we can modify __e820_add_region() and the mem boot option can work for
> efi environment.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  arch/x86/kernel/e820.c |   29 +++++++++++++++++++++++++----
>  1 files changed, 25 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 4185797..20bc467 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -47,6 +47,7 @@ unsigned long pci_mem_start = 0xaeedbabe;
>  #ifdef CONFIG_PCI
>  EXPORT_SYMBOL(pci_mem_start);
>  #endif
> +static u64 mem_limit = ~0ULL;
>  
>  /*
>   * This function checks if any part of the range <start,end> is mapped
> @@ -119,6 +120,20 @@ static void __init __e820_add_region(struct e820map *e820x, u64 start, u64 size,
>  		return;
>  	}
>  
> +	if (start >= mem_limit) {
> +		printk(KERN_ERR "e820: ignoring [mem %#010llx-%#010llx]\n",
> +		       (unsigned long long)start,
> +		       (unsigned long long)(start + size - 1));
> +		return;
> +	}
> +
> +	if (mem_limit - start < size) {
> +		printk(KERN_ERR "e820: ignoring [mem %#010llx-%#010llx]\n",
> +		       (unsigned long long)mem_limit,
> +		       (unsigned long long)(start + size - 1));
> +		size = mem_limit - start;
> +	}
> +
>  	e820x->map[x].addr = start;
>  	e820x->map[x].size = size;
>  	e820x->map[x].type = type;
> @@ -809,7 +824,7 @@ static int userdef __initdata;
>  /* "mem=nopentium" disables the 4MB page tables. */
>  static int __init parse_memopt(char *p)
>  {
> -	u64 mem_size;
> +	char *oldp;
>  
>  	if (!p)
>  		return -EINVAL;
> @@ -825,11 +840,11 @@ static int __init parse_memopt(char *p)
>  	}
>  
>  	userdef = 1;
> -	mem_size = memparse(p, &p);
> +	oldp = p;
> +	mem_limit = memparse(p, &p);
>  	/* don't remove all of memory when handling "mem={invalid}" param */
> -	if (mem_size == 0)
> +	if (mem_limit == 0 || p == oldp)
>  		return -EINVAL;
> -	e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);
>  
>  	return 0;
>  }
> @@ -881,6 +896,12 @@ early_param("memmap", parse_memmap_opt);
>  
>  void __init finish_e820_parsing(void)
>  {
> +	if (mem_limit != ~0ULL) {
> +		userdef = 1;
> +		e820_remove_range(mem_limit, ULLONG_MAX - mem_limit,
> +				  E820_RAM, 1);
> +	}
> +
>  	if (userdef) {
>  		u32 nr = e820.nr_map;
>