On 2021/2/5 0:10, Bjorn Helgaas wrote:

[+cc Masahiro, Michal, linux-kbuild, linux-kernel]

On Thu, Feb 04, 2021 at 07:30:15PM +0800, Yicong Yang wrote:

quoted

From: Junhao He <redacted>

Use subdir-ccflags-* instead of ccflags-* to inherit the debug
settings from Kconfig when traversing subdirectories.

So I guess the current behavior is:

  If CONFIG_PCI_DEBUG=y, add -DDEBUG to CFLAGS in the current
  directory, but not in any subdirectories

and the behavior after this patch is:

  If CONFIG_PCI_DEBUG=y, add -DDEBUG to CFLAGS in the current
  directory and any subdirectories

Is that right?  That makes sense to me.  I wonder if any other places
have this issue?

that's right. we didn't check other places, but some have individual config
in their sub-directory as you mentioned below.

'git grep "^ccflags.*-DDEBUG"' finds a few cases where subdirectories
use their own debug config options, e.g.,

  drivers/i2c/Makefile:ccflags-$(CONFIG_I2C_DEBUG_CORE) := -DDEBUG
  drivers/i2c/algos/Makefile:ccflags-$(CONFIG_I2C_DEBUG_ALGO) := -DDEBUG
  drivers/i2c/busses/Makefile:ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
  drivers/i2c/muxes/Makefile:ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG

But some have subdirectories that look like they probably should be
included by using subdir-ccflags, e.g.,

  drivers/base/Makefile:ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
  drivers/base/power/Makefile:ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
    # drivers/base/{firmware_loader,regmap,test}/ not included

  drivers/hwmon/Makefile:ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG
    # drivers/hwmon/{occ,pmbus}/ not included

  drivers/pps/Makefile:ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG
  drivers/pps/clients/Makefile:ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG
    # drivers/pps/generators/ not included

There are many more places that add -DDEBUG to ccflags-y that *don't*
have subdirectories.

I wonder the default should be that we use subdir-ccflags all the
time, and use ccflags only when we actually want different
CONFIG_*_DEBUG options for subdirectories.

agree. if there is no debug config in the sub-directory, the
config should be inherited from its parent directory using subdir-ccflags.

we can post a separate serial to issue other places.

Thanks,
Yicong

quoted

Signed-off-by: Junhao He <redacted>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index 11cc794..d62c4ac 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile

@@ -36,4 +36,4 @@ obj-$(CONFIG_PCI_ENDPOINT)	+= endpoint/
 obj-y				+= controller/
 obj-y				+= switch/
 
-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG
+subdir-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG

-- 
2.8.1

.