On Tue, 24 Jan 2017, Joe Perches wrote:
> On Tue, 2017-01-24 at 18:40 -0800, Dan Williams wrote: > > On Tue, Jan 24, 2017 at 6:37 PM, Joe Perches <j...@perches.com> wrote: > > > On Wed, 2017-01-25 at 00:54 +0530, Bhumika Goyal wrote: > > > > Declare device_type structure as const as it is only stored in the > > > > type field of a device structure. This field is of type const, so add > > > > const to declaration of device_type structure. > > > > > > > > File size before: > > > > text data bss dec hex filename > > > > 19278 3199 16 22493 57dd nvdimm/namespace_devs.o > > > > > > > > File size after: > > > > text data bss dec hex filename > > > > 19929 3160 16 23105 5a41 nvdimm/namespace_devs.o > > > > > > Fine, but are you sure about the sizes? > > > > > > It seems odd the text went up 651 bytes > > > while the data went down just 39 bytes. > > > > > > > Right, the size data wasn't why I applied it. It was the general rule > > of "make function pointer data read-only whenever possible to > > eliminate a kernel attack vector". > > Exactly the correct reason it's a fine patch and one > that should be applied. > > > Bhumika, you might want to mention > > this as the motivating reason to apply the patch if you do more of > > these changes. > > Regardless, the object sizes are still odd. > > The config should be mentioned because actually, > the commonly compiles sizes reported are not correct. > > with an x86-64 defconfig I get: > > $ size drivers/nvdimm/namespace_devs.o* > text data bss dec hex filename > 14615 519 16 15150 3b2e > drivers/nvdimm/namespace_devs.o.new > 14439 695 16 15150 3b2e > drivers/nvdimm/namespace_devs.o.old What does the data column actually represent? I tried size on the .o file generated from: commit a65f0161f4d69d6738d4821e649448312cd818e2 Author: Stephen Rothwell <s...@canb.auug.org.au> Date: Tue Jan 17 15:22:28 2017 +1100 with CONFIG_X86_64=y and I get: text data bss dec hex filename 19726 3480 16 23222 5ab6 drivers/nvdimm/namespace_devs.o but when I run objdump -sh drivers/nvdimm/namespace_devs.o, I find a .data segment of size 1008 and a .data.unlikely segment of size 8, which don't match up with the results of size. julia
