-----Original Message-----
From: devel@edk2.groups.io <devel@edk2.groups.io> On
Behalf Of Ard Biesheuvel
Sent: Wednesday, June 10, 2020 12:30 PM
To: devel@edk2.groups.io
Cc: Ard Biesheuvel <ard.biesheu...@arm.com>; Kinney,
Michael D <michael.d.kin...@intel.com>; Gao, Liming
<liming....@intel.com>
Subject: [edk2-devel] [PATCH v2] MdePkg/BasePrintLib:
avoid absolute addresses for error strings
The mStatusString[] array is constructed as an array of
pointer-to-char,
which means that on X64 or AARCH64, it is emitted as a
single linear list
of 64-bit quantities, each containing the absolute
address of one of the
string literals in memory.
This means that each string takes up 8 bytes of
additional space, along
with 2 bytes of relocation data. It also means that
extra work needs to
be done at runtime to process these relocations, every
time a module is
loaded that incorporates this library.
So fix both issues, by splitting mStatusString into two
arrays of char
arrays. The memory footprint decreases from 955 to 843
bytes, and given
that in the latter case, the overhead consists of 278
NUL characters rather
than 390 bytes worth of absolute addresses and
relocation records, the size
of a compressed image is reduced even further. For
example, when building
ArmVirtQemu.dsc in RELEASE mode for AARCH64 with the
GCC5 profile, I get:
Before
FV Space Information
FVMAIN [100%Full] 5329920 total, 5329920 used, 0 free
FVMAIN_COMPACT [38%Full] 2093056 total, 811840 used,
1281216 free
After
FV Space Information
FVMAIN [100%Full] 5321728 total, 5321728 used, 0 free
FVMAIN_COMPACT [38%Full] 2093056 total, 809696 used,
1283360 free
So the uncompressed contents of the compressed image are
8 KB smaller,
whereas the resulting flash image (consisting of the
compressed image
along with SEC, PEI_CORE and a set of PEIMs that execute
in place) is
~2 KB smaller.
Cc: "Kinney, Michael D" <michael.d.kin...@intel.com>
Cc: "Gao, Liming" <liming....@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheu...@arm.com>
---
v2:
- split off this patch from the StandaloneMmPkg series,
since they are not
interdependent anyway, and so they can be discussed
separately
- remove mention of StandaloneMmPkg from the commit log
- the space savings
by themselves are sufficient justification
- update the before/after numbers with the current
results
- split the warnings and errors into a separate array,
so that the latter
can use smaller entries
- clarify the commit log to explain the effect on
compressed as well as
XIP images (which both get smaller)
MdePkg/Library/BasePrintLib/PrintLibInternal.c | 9
++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git
a/MdePkg/Library/BasePrintLib/PrintLibInternal.c
b/MdePkg/Library/BasePrintLib/PrintLibInternal.c
index b6ec5ac4fbb9..522c3bb5dcb9 100644
--- a/MdePkg/Library/BasePrintLib/PrintLibInternal.c
+++ b/MdePkg/Library/BasePrintLib/PrintLibInternal.c
@@ -27,13 +27,16 @@
GLOBAL_REMOVE_IF_UNREFERENCED CONST CHAR8 mHexStr[] =
{'0','1','2','3','4','5','6','7','8','9','A','B','C','D'
,'E','F'};
-GLOBAL_REMOVE_IF_UNREFERENCED CONST CHAR8 * CONST
mStatusString[] = {
+GLOBAL_REMOVE_IF_UNREFERENCED CONST CHAR8
mWarningString[][25] = {
"Success", // RETURN_SUCCESS
= 0
"Warning Unknown Glyph", //
RETURN_WARN_UNKNOWN_GLYPH = 1
"Warning Delete Failure", //
RETURN_WARN_DELETE_FAILURE = 2
"Warning Write Failure", //
RETURN_WARN_WRITE_FAILURE = 3
"Warning Buffer Too Small", //
RETURN_WARN_BUFFER_TOO_SMALL = 4
"Warning Stale Data", //
RETURN_WARN_STALE_DATA = 5
+};
+
+GLOBAL_REMOVE_IF_UNREFERENCED CONST CHAR8
mErrorString[][21] = {
"Load Error", // RETURN_LOAD_ERROR
= 1 | MAX_BIT
"Invalid Parameter", //
RETURN_INVALID_PARAMETER = 2 | MAX_BIT
"Unsupported", //
RETURN_UNSUPPORTED = 3 | MAX_BIT
@@ -996,12 +999,12 @@ BasePrintLibSPrintMarker (
//
Index = Status & ~MAX_BIT;
if (Index > 0 && Index <=
ERROR_STATUS_NUMBER) {
- ArgumentString = mStatusString [Index +
WARNING_STATUS_NUMBER];
+ ArgumentString = mErrorString [Index - 1];
}
} else {
Index = Status;
if (Index <= WARNING_STATUS_NUMBER) {
- ArgumentString = mStatusString [Index];
+ ArgumentString = mWarningString [Index];
}
}
if (ArgumentString == ValueBuffer) {
--
2.26.2
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