Re: [Qemu-devel] [RFC 10/15] s390-bios: Support for running format-0/1 channel programs

[Christian Borntraeger]

On 07/05/2018 07:25 PM, Jason J. Herne wrote:
> From: "Jason J. Herne" <jjhe...@linux.vnet.ibm.com>

> +void await_io_int(uint16_t sch_no)
> +{
> +    /*
> +     * wait_psw and ctl6 must be static to avoid stack allocation as gcc 
> cannot
> +     * align stack variables. The stctg, lctlg and lpswe instructions require
> +     * that their operands be aligned on an 8-byte boundary.
> +    */

In fact, the ABI guarantees that the stack is always 8 byte aligned and gcc 
should 
align any uint64_t to 8 byte as well on the stack.

> +    static uint64_t ctl6 __attribute__((__aligned__(8)));
> +    static PSW wait_psw;
> +