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

Paulius Zaleckas
2010-03-31T12:11:04Z

On 03/25/2010 06:26 PM, Nicolas Pitre wrote:
> 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>

David,

Will you take this patch?
Or you are waiting till I will add all Cc as Jamie suggested?

>
>> ---
>>
>> 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;
>> }
>>