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Re: [Qemu-trivial] [Qemu-devel] [PATCH] tpm_tis: fix format for 64bit va
From: |
Eric Blake |
Subject: |
Re: [Qemu-trivial] [Qemu-devel] [PATCH] tpm_tis: fix format for 64bit variable |
Date: |
Tue, 31 Mar 2015 08:15:01 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 03/31/2015 08:09 AM, Eric Blake wrote:
> On 03/31/2015 07:27 AM, Stefan Berger wrote:
>> Signed-off-by: Stefan Berger <address@hidden>
>> ---
>> hw/tpm/tpm_tis.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
>> index 815c8ea..52e0148 100644
>> --- a/hw/tpm/tpm_tis.c
>> +++ b/hw/tpm/tpm_tis.c
>> @@ -814,7 +814,7 @@ static void tpm_tis_mmio_write_intern(void *opaque,
>> hwaddr addr,
>> tis->loc[locty].state == TPM_TIS_STATE_COMPLETION) {
>> /* drop the byte */
>> } else {
>> - DPRINTF("tpm_tis: Data to send to TPM: %08x (size=%d)\n",
>> + DPRINTF("tpm_tis: Data to send to TPM: %08lx (size=%d)\n",
>
> NACK. When printing uint64_t val, you HAVE to use PRIx64, not lx, for
> the sake of 32-bit platforms.
Furthermore, you could have caught this much sooner if you fix the
definition of DPRINTF. This file used:
#ifdef DEBUG_TIS
#define DPRINTF(fmt, ...) \
do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) \
do { } while (0)
#endif
which is bad, because the compiler CAN'T see the type mismatch unless
you turn debugging on (alas, we have a LOT of files in the code base
with similar bad patterns). A better example is hw/display/cg3.c:
/* Change to 1 to enable debugging */
#define DEBUG_CG3 0
...
#define DPRINTF(fmt, ...) do { \
if (DEBUG_CG3) { \
printf("CG3: " fmt , ## __VA_ARGS__); \
} \
} while (0);
where now the compiler can unconditionally do -Wformat checking and
avoid bit-rot, even if debug printing is never turned on, and without
penalizing code size when debugging is off.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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