When building position independent (PIC) ELF objects, the GCC compiler
assumes that each symbol with external linkage may potentially end up
being exported from a shared library, which means that each of those
symbols may be subject to symbol preemption, i.e., the executable
linking to the shared library at runtime may override symbols exported
by the shared library, and every internal reference held by the shared
library itself *must* be made to point to the overridden version instead.
For this reason, PIC code symbol references always go via the Global
Offset Table (GOT), even if the code in question references symbols that
are defined in the same compilation unit. The GOT refers to each symbol
by absolute address, and so each entry is subject to runtime relocation.
Since not every symbol with external linkage is ultimately exported from
a shared library, the GCC compiler allows control over symbol visibility
using attributes, command line arguments and pragmas, where 'protected'
means that the symbol is only referenced by the shared library itself.
Due to the poor hygiene in EDK2 regarding the use of the 'static'
modifier, many symbols that are local to their compilation unit end up
being referenced indirectly via the GOT when building PIC code.
In UEFI, there are no shared libraries and so there is no need to deal
with symbol preemption, and we can mark every symbol reference protected.
The only method that applies to all symbol definitions as well as
declarations is the #pragma. So set the visibility 'protected' pragma when
building PIC code for X64 using GCC. Note that this affects code generated
with the -fpie compiler switch as well as the -fpic compiler switch.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Tested-By: Liming Gao <liming.gao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
C4701 & C4703 may cause false positive issues.
They have been disabled in VS2013.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19111 6f19259b-4bc3-4df7-8a09-765794883524
As they may be raised as false positive in building.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Shumin Qiu <shumin.qiu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16594 6f19259b-4bc3-4df7-8a09-765794883524
Some compilers may define __USER_LABEL_PREFIX__ to determine the
prefix used with ASM_PFX. Otherwise, IA32 will use a single underscore
'_' character, and all other architectures will use an empty prefix.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16019 6f19259b-4bc3-4df7-8a09-765794883524
2. Remove the #defines and add the extern declarations for gEfiDebugPortVariableGuid and gEfiDebugPortDevicePathGuid.
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: michael.d.kinney@intel.com
Reviewed-by: Star Zeng <star.zeng@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14465 6f19259b-4bc3-4df7-8a09-765794883524
Original, some code directly judge the value of these macros, but linux ICC compiler will report error as "zero used for undefined preprocessing identifier". So it is better judge whether these macros are defined before accessing their value.
2, Use #if defined() style to replace #ifdef style.
It is good to keep consistent style for this case.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7596 6f19259b-4bc3-4df7-8a09-765794883524
trunk/edk2/MdePkg/Include/Ia32/ProcessorBind.h:
trunk/edk2/MdePkg/Include/Ipf/ProcessorBind.h:
* Do not ignore this warning (Intel Compiler warning #593; Local
Variable is set, but not used.) We will attempt to clean up
code that generates this particular warning.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@6083 6f19259b-4bc3-4df7-8a09-765794883524
Ard Biesheuvel
Liming Gao
Shumin Qiu
Chen Fan
Jordan Justen
lgao4
hhtian
geekboy15a
eric_tian
mdkinney
pkandel
xli24
jljusten
klu2
qhuang8
gikidy
vanjeff