[Qemu-devel] [PATCH v2 1/4] coding_style: add point about 0x in trace-events

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 CODING_STYLE | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/CODING_STYLE b/CODING_STYLE
index 2fa0c0b65b..2e6a0507be 100644
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -123,3 +123,26 @@ We use traditional C-style /* */ comments and avoid // comments.
 
 Rationale: The // form is valid in C99, so this is purely a matter of
 consistency of style. The checkpatch script will warn you about this.
+
+8. trace-events style
+
+In trace-events files use '0x' prefix to specify hex numbers, as in:
+
+some_trace(unsigned x, uint64_t y) "x 0x%x y 0x" PRIx64
+
+The exclusion is a group of numbers, separated by symbols '.', '/', ':', ' ':
+
+some_other_trace(unsigned a, unsigned b, unsigned c) "num %x.%x.%x"
+
+However, you can use '0x' for such groups if you want. Anyway, be sure that
+it is obvious that numbers are in hex, ex.:
+
+data_dump(uint8_t c1, uint8_t c2, uint8_t c3) "bytes (in hex): %02x %02x %02x"
+
+For consistency do not use printf flag '#', like '%#x'.
+
+Rationale: hex numbers are hard to read in logs when there no 0x prefix,
+especially when (occasionally) the representation doesn't contain any letters
+and especially in one line with other decimal numbers. Number groups are
+allowed to not use '0x' because for some things notations like %x.%x.%x are
+used not only in Qemu. Also dumping raw data bytes with '0x' is less readable.
-- 
2.11.1