Re: [Qemu-devel] [RFC PATCH v2 1/8] pc-bios/s390-ccw: Move libc functions to separate header

[Christian Borntraeger]

On 07/07/2017 12:26 PM, Thomas Huth wrote:
> The upcoming netboot code will use the libc from SLOF. To be able
> to still use s390-ccw.h there, the libc related functions in this
> header have to be moved to a different location.
> And while we're at it, remove the duplicate memcpy() function from
> sclp.c.
> 
> Signed-off-by: Thomas Huth <address@hidden>

one suggestion below, but 

Reviewed-by: Christian Borntraeger <address@hidden>

for change and no change

[...]
> +static inline void *memcpy(void *s1, const void *s2, size_t n)
> +{
> +    uint8_t *p1 = s1;
> +    const uint8_t *p2 = s2;
> +
> +    while (n--) {
> +        p1[n] = p2[n];
> +    }
> +    return s1;
> +}

Not that it matters, and no idea if moving forward like in the for loop below
might allow gcc to generate better code, but a for loop like below will be the 
same direction as the MVC instruction. Can you double check if this generates
better code?

> -static void _memcpy(char *dest, const char *src, int len)
> -{
> -   int i;
> -     for (i = 0; i < len; i++)
> -        dest[i] = src[i];
> -}
> -