Hi Patrick,
On 13 December 2017 at 03:15, Patrick Brünn P.Bruenn@beckhoff.com wrote:
From: Patrick Brünn Sent: Donnerstag, 30. November 2017 12:22
Since commit 8eafae209c35932d9a6560809c55ee4641534236 my mx53cx9020_defconfig stopped booting. ... It seems important to read into do_fat_read_at_block. If I allocate a temporary buffer and read into that one, I still can't boot. That seems strange to me as, I couldn't find any uninitialized access to do_fat_read_at_block anywhere.
I believe I finally tracked it down to the linker.
Without accessing do_fat_read_at_block within fat.c, I find .bss. do_fat_read_at_block as "discarded input section" in my u-boot.map
With a patch like this: diff --git a/fs/fat/fat.c b/fs/fat/fat.c index d16883fa10..8e70fdbc8d 100644 --- a/fs/fat/fat.c +++ b/fs/fat/fat.c @@ -1157,6 +1157,7 @@ int fat_opendir(const char *filename, struct fs_dir_stream **dirsp) return -ENOMEM; memset(dir, 0, sizeof(*dir));
if (do_fat_read_at_block[0])printf("value doesn't matter, the access is important\n");ret = fat_itr_root(&dir->itr, &dir->fsdata); if (ret) goto fail_free_dir;The section isn't discarded and my board boots again.
Another workaround would be: diff --git a/arch/arm/config.mk b/arch/arm/config.mk index 124b44a337..02f61fcc3c 100644 --- a/arch/arm/config.mk +++ b/arch/arm/config.mk @@ -17,7 +17,7 @@ CFLAGS_NON_EFI := -fno-pic -ffixed-r9 -ffunction-sections -fdata-sections CFLAGS_EFI := -fpic -fshort-wchar
LDFLAGS_FINAL += --gc-sections -PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections \ +PLATFORM_RELFLAGS += -ffunction-sections \ -fno-common -ffixed-r9 PLATFORM_RELFLAGS += $(call cc-option, -msoft-float) \ $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,))
Or a hack like: diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds index 37d4c605ac..b916cbc733 100644 --- a/arch/arm/cpu/u-boot.lds +++ b/arch/arm/cpu/u-boot.lds @@ -219,6 +219,7 @@ SECTIONS }
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.bss.do_fat_read_at_block)); KEEP(*(.__bss_end)); }I also tried to mark do_fat_read_at_block as: volatile, __used and/or __attribute__((externally_visible))
This doesn't help.
Moving it into fat_write.c doesn't help either(with/without static)
My toolchain is: ~/u-boot$ arm-linux-gnueabihf-gcc -v Using built-in specs. COLLECT_GCC=arm-linux-gnueabihf-gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc-cross/arm-linux-gnueabihf/6/lto-wrapper Target: arm-linux-gnueabihf Configured with: ../src/configure -v --with-pkgversion='Debian 6.3.0-18' --with-bugurl=file:///usr/share/doc/gcc-6/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-6 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libitm --disable-libquadmath --enable-plugin --enable-default-pie --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-6-armhf-cross/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-6-armhf-cross --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-6-armhf-cross --with-arch-directory=arm --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libgcj --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-sjlj-exceptions --with-arch=armv7-a --with-fpu=vfpv3-d16 --with-float=hard --with-mode=thumb --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=arm-linux-gnueabihf --program-prefix=arm-linux-gnueabihf- --includedir=/usr/arm-linux-gnueabihf/include Thread model: posix gcc version 6.3.0 20170516 (Debian 6.3.0-18)
~/u-boot$ arm-linux-gnueabihf-ld -v GNU ld (GNU Binutils for Debian) 2.28
Does anyone have an idea what else I can try to prevent my linker from removing do_fat_read_at_block?
This doesn't seem to be used unless you have enabled CONFIG_FAT_WRITE. Have you?
I wonder if the problem is somewhere else, and the presence of this buffer is just moving things apart in the data space, and thus masking the problem?
Regards, Simon