Re: [PATCH v2] MTD: Fix Orion NAND driver compilation with ARM OABI

Nicolas Pitre
2010-03-25T16:26:47Z

On Thu, 25 Mar 2010, Paulius Zaleckas wrote:

> We must tell GCC to use even register for variable passed
> to ldrd instruction. Without this patch GCC 4.2.1 puts this
> variable to r2/r3 on EABI and r3/r4 on OABI, so force it to
> r2/r3. This does not change anything when EABI and OABI
> compilation works OK.
>
> Without this patch and with OABI I get:
> CC drivers/mtd/nand/orion_nand.o
> /tmp/ccMkwOCs.s: Assembler messages:
> /tmp/ccMkwOCs.s:63: Error: first destination register must be even -- `ldrd r3,[ip]'
> make[5]: *** [drivers/mtd/nand/orion_nand.o] Error 1
>
> Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>

Acked-by: Nicolas Pitre <nico@fluxnic.net>

> ---
>
> drivers/mtd/nand/orion_nand.c | 8 +++++++-
> 1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mtd/nand/orion_nand.c b/drivers/mtd/nand/orion_nand.c
> index f59c074..d60fc57 100644
> --- a/drivers/mtd/nand/orion_nand.c
> +++ b/drivers/mtd/nand/orion_nand.c
> @@ -60,7 +60,13 @@ static void orion_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
> }
> buf64 = (uint64_t *)buf;
> while (i < len/8) {
> - uint64_t x;
> + /*
> + * Since GCC has no proper constraint (PR 43518)
> + * force x variable to r2/r3 registers as ldrd instruction
> + * requires first register to be even.
> + */
> + register uint64_t x asm ("r2");
> +
> asm volatile ("ldrd\t%0, [%1]" : "=&r" (x) : "r" (io_base));
> buf64[i++] = x;
> }
>