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[Qemu-devel] [PULL 5/9] coding_style: add point about 0x in trace-events
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 5/9] coding_style: add point about 0x in trace-events |
Date: |
Tue, 1 Aug 2017 14:16:14 +0100 |
From: Vladimir Sementsov-Ogievskiy <address@hidden>
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Message-id: address@hidden
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
CODING_STYLE | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/CODING_STYLE b/CODING_STYLE
index 2fa0c0b65b..12ba58ee29 100644
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -123,3 +123,38 @@ 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
+
+8.1 0x prefix
+
+In trace-events files, use a '0x' prefix to specify hex numbers, as in:
+
+some_trace(unsigned x, uint64_t y) "x 0x%x y 0x" PRIx64
+
+An exception is made for groups of numbers that are hexadecimal by
+convention and separated by the symbols '.', '/', ':', or ' ' (such as
+PCI bus id):
+
+another_trace(int cssid, int ssid, int dev_num) "bus id: %x.%x.%04x"
+
+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"
+
+Rationale: hex numbers are hard to read in logs when there is 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.
+
+8.2 '#' printf flag
+
+Do not use printf flag '#', like '%#x'.
+
+Rationale: there are two ways to add a '0x' prefix to printed number: '0x%...'
+and '%#...'. For consistency the only one way should be used. Arguments for
+'0x%' are:
+ - it is more popular
+ - '%#' omits the 0x for the value 0 which makes output inconsistent
--
2.13.3
- [Qemu-devel] [PULL 0/9] Tracing patches, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 2/9] trace: ensure unique function / variable names per .stp file, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 1/9] trace: ensure .stp files are rebuilt if trace tool source changes, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 3/9] trace: add TRACE_<event>_BACKEND_DSTATE(), Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 4/9] trace: add trace_event_get_state_backends(), Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 5/9] coding_style: add point about 0x in trace-events,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 6/9] trace-events: fix code style: %# -> 0x%, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 7/9] checkpatch: check trace-events code style, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 9/9] monitor: Reduce handle_qmp_command() tracing overhead, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 8/9] trace-events: fix code style: print 0x before hex numbers, Stefan Hajnoczi, 2017/08/01
- Re: [Qemu-devel] [PULL 0/9] Tracing patches, no-reply, 2017/08/01
- Re: [Qemu-devel] [PULL 0/9] Tracing patches, Peter Maydell, 2017/08/01