Re: [Qemu-devel] [PATCH] sh4: add signal handling support for user space emulator

[Paul Mundt]

On Wed, Nov 21, 2007 at 05:16:55PM +0900, Magnus Damm wrote:
> +#define MOVW(n)  (0x9300|((n)-2)) /* Move mem word at PC+n to R3 */
> +#define TRAP_NOARG 0xc310         /* Syscall w/no args (NR in R3) SH3/4 */
> +#define OR_R0_R0 0x200b           /* or r0,r0 (insert to avoid hardware bug) 
> */
This is legacy SH-4 errata, and does not pop up on any of the other
parts. These days all SH-4 parts return through the vsyscall page, where
we deal with this errata directly without having to push it in to the
return frame. While you might not want to deal with implementing the
vsyscall page, there's definitely no point in crapping up the return
frame with this chip errata in the general case.