Re: [PATCH 17/18] x86/efi: create new early memory allocator

[Jan Beulich]

>>> On 30.01.15 at 18:54, <address@hidden> wrote:
> --- a/xen/arch/x86/efi/efi-boot.h
> +++ b/xen/arch/x86/efi/efi-boot.h
> @@ -103,9 +103,35 @@ static void __init relocate_trampoline(unsigned long 
> phys)
>          *(u16 *)(*trampoline_ptr + (long)trampoline_ptr) = phys >> 4;
>  }
>  
> +#define __MALLOC_SIZE        65536
> +
> +static char __malloc_mem[__MALLOC_SIZE];
> +static char *__malloc_free = NULL;
> +
> +static void __init *__malloc(size_t size)

Please do away with all these prefixing underscores.

> +{
> +    void *ptr;
> +
> +    /*
> +     * Init __malloc_free on runtime. Static initialization
> +     * will not work because it puts virtual address there.
> +     */
> +    if ( __malloc_free == NULL )
> +        __malloc_free = __malloc_mem;
> +
> +    ptr = __malloc_free;
> +
> +    __malloc_free += size;
> +
> +    if ( __malloc_free - __malloc_mem > sizeof(__malloc_mem) )
> +        blexit(L"Out of static memory\r\n");
> +
> +    return ptr;
> +}

You're ignoring alignment requirements here altogether.

> @@ -192,12 +218,7 @@ static void __init 
> efi_arch_process_memory_map(EFI_SYSTEM_TABLE *SystemTable,
>  
>  static void *__init efi_arch_allocate_mmap_buffer(UINTN *map_size)
>  {
> -    place_string(&mbi.mem_upper, NULL);
> -    mbi.mem_upper -= *map_size;
> -    mbi.mem_upper &= -__alignof__(EFI_MEMORY_DESCRIPTOR);
> -    if ( mbi.mem_upper < xen_phys_start )
> -        return NULL;
> -    return (void *)(long)mbi.mem_upper;
> +    return __malloc(*map_size);
>  }

Which then even suggests that _if_ we go this route, this could be
shared with ARM (and hence become common code again).

Jan