[U-Boot] [PATCH 0/2] tegra2: Fixes for running mainline U-Boot.
The following series contains two patches that allow mainline U-Boot to boot standalone on Tegra2-based boards. It assumes the standard NVIDIA flashing tools as provided by the Linux4Tegra package. The series is based on patches that have already been reviewed but haven't been merged upstream yet. They are available in patchwork here:
http://patchwork.ozlabs.org/patch/122888 http://patchwork.ozlabs.org/patch/122887 http://patchwork.ozlabs.org/patch/122889 http://patchwork.ozlabs.org/patch/123845 (9 patches)
Thierry Reding (2): tegra2: Always build with USE_PRIVATE_LIBGCC=yes. tegra2: Change CONFIG_SYS_TEXT_BASE to 0x00108000.
arch/arm/cpu/armv7/tegra2/config.mk | 2 ++ include/configs/tegra2-common.h | 2 +- 2 files changed, 3 insertions(+), 1 deletions(-)
The AVP on Tegra2 doesn't boot properly when U-Boot is linked against the GCC provided libgcc. To work around this, always build and link against a private libgcc for Tegra2-based boards.
Signed-off-by: Thierry Reding thierry.reding@avionic-design.de --- arch/arm/cpu/armv7/tegra2/config.mk | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/cpu/armv7/tegra2/config.mk b/arch/arm/cpu/armv7/tegra2/config.mk index 8f9bdc9..2303dba 100644 --- a/arch/arm/cpu/armv7/tegra2/config.mk +++ b/arch/arm/cpu/armv7/tegra2/config.mk @@ -29,3 +29,5 @@ ifdef CONFIG_TEGRA2 CFLAGS_arch/arm/lib/board.o += -march=armv4t endif + +USE_PRIVATE_LIBGCC = yes
On Thu, Nov 17, 2011 at 2:04 AM, Thierry Reding thierry.reding@avionic-design.de wrote:
The AVP on Tegra2 doesn't boot properly when U-Boot is linked against the GCC provided libgcc. To work around this, always build and link against a private libgcc for Tegra2-based boards.
Signed-off-by: Thierry Reding thierry.reding@avionic-design.de
Tested-by: Simon Glass sjg@chromium.org
arch/arm/cpu/armv7/tegra2/config.mk | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/cpu/armv7/tegra2/config.mk b/arch/arm/cpu/armv7/tegra2/config.mk index 8f9bdc9..2303dba 100644 --- a/arch/arm/cpu/armv7/tegra2/config.mk +++ b/arch/arm/cpu/armv7/tegra2/config.mk @@ -29,3 +29,5 @@ ifdef CONFIG_TEGRA2 CFLAGS_arch/arm/lib/board.o += -march=armv4t endif
+USE_PRIVATE_LIBGCC = yes
1.7.7.3
Dear Thierry Reding,
In message 1321524246-5187-2-git-send-email-thierry.reding@avionic-design.de you wrote:
The AVP on Tegra2 doesn't boot properly when U-Boot is linked against the GCC provided libgcc. To work around this, always build and link against a private libgcc for Tegra2-based boards.
I notice this patch only now, when pulling in from u-boot-arm.
I will accept this only temporarily. Why don't you use a working tool chain instead, or fix the one you are using?
Best regards,
Wolfgang Denk
On 01/05/2012 08:50 AM, Wolfgang Denk wrote:
Dear Thierry Reding,
In message 1321524246-5187-2-git-send-email-thierry.reding@avionic-design.de you wrote:
The AVP on Tegra2 doesn't boot properly when U-Boot is linked against the GCC provided libgcc. To work around this, always build and link against a private libgcc for Tegra2-based boards.
I notice this patch only now, when pulling in from u-boot-arm.
I will accept this only temporarily. Why don't you use a working tool chain instead, or fix the one you are using?
I believe the issue isn't that the toolchain is broken, but due to the mix of multiple CPU types on Tegra, all of which run the same U-Boot binary.
U-Boot starts execution on the AVP CPU, an ARMv4(?) CPU. U-Boot then inits the main CPUs, ARMv7 Cortex A9s, and arranges for them to continue running U-Boot.
The libraries included in the toolchain are built for the ARMv7 CPUs, and hence fail to operate correctly when used by the portion of U-Boot which runs on the ARMv4 CPU, presumably due to ISA differences. IIRC, there are overrides in the U-Boot build process such that some/all of U-Boot is built so it'll run on ARMv4 OK, which is why using libgcc built by U-Boot solves this.
Hi Stephen,
On Thu, Jan 5, 2012 at 8:53 AM, Stephen Warren swarren@nvidia.com wrote:
On 01/05/2012 08:50 AM, Wolfgang Denk wrote:
Dear Thierry Reding,
In message 1321524246-5187-2-git-send-email-thierry.reding@avionic-design.de you wrote:
The AVP on Tegra2 doesn't boot properly when U-Boot is linked against the GCC provided libgcc. To work around this, always build and link against a private libgcc for Tegra2-based boards.
I notice this patch only now, when pulling in from u-boot-arm.
I will accept this only temporarily. Why don't you use a working tool chain instead, or fix the one you are using?
I believe the issue isn't that the toolchain is broken, but due to the mix of multiple CPU types on Tegra, all of which run the same U-Boot binary.
U-Boot starts execution on the AVP CPU, an ARMv4(?) CPU. U-Boot then inits the main CPUs, ARMv7 Cortex A9s, and arranges for them to continue running U-Boot.
The libraries included in the toolchain are built for the ARMv7 CPUs, and hence fail to operate correctly when used by the portion of U-Boot which runs on the ARMv4 CPU, presumably due to ISA differences. IIRC, there are overrides in the U-Boot build process such that some/all of U-Boot is built so it'll run on ARMv4 OK, which is why using libgcc built by U-Boot solves this.
Yes that's right, but actually I have never delved into exactly why. Perhaps it is an integer divide or internal memcpy() call early in the code. We might be able to find the offending C library code, given enough time, and perhaps arrange not to call it. A little fragile though.
Regards, Simon
-- nvpublic
Simon,
-----Original Message----- From: sjg@google.com [mailto:sjg@google.com] On Behalf Of Simon Glass Sent: Thursday, January 05, 2012 10:07 AM To: Stephen Warren Cc: Wolfgang Denk; Thierry Reding; u-boot@lists.denx.de; Tom Warren Subject: Re: [U-Boot] [PATCH 1/2] tegra2: Always build with USE_PRIVATE_LIBGCC=yes.
Hi Stephen,
On Thu, Jan 5, 2012 at 8:53 AM, Stephen Warren swarren@nvidia.com wrote:
On 01/05/2012 08:50 AM, Wolfgang Denk wrote:
Dear Thierry Reding,
In message <1321524246-5187-2-git-send-email-thierry.reding@avionic-
design.de> you wrote:
The AVP on Tegra2 doesn't boot properly when U-Boot is linked against the GCC provided libgcc. To work around this, always build and link against a private libgcc for Tegra2-based boards.
I notice this patch only now, when pulling in from u-boot-arm.
I will accept this only temporarily. Why don't you use a working tool chain instead, or fix the one you are using?
I believe the issue isn't that the toolchain is broken, but due to the mix of multiple CPU types on Tegra, all of which run the same U-Boot
binary.
U-Boot starts execution on the AVP CPU, an ARMv4(?) CPU. U-Boot then inits the main CPUs, ARMv7 Cortex A9s, and arranges for them to continue running U-Boot.
The libraries included in the toolchain are built for the ARMv7 CPUs, and hence fail to operate correctly when used by the portion of U-Boot which runs on the ARMv4 CPU, presumably due to ISA differences. IIRC, there are overrides in the U-Boot build process such that some/all of U-Boot is built so it'll run on ARMv4 OK, which is why using libgcc built by U-Boot solves this.
Yes that's right, but actually I have never delved into exactly why. Perhaps it is an integer divide or internal memcpy() call early in the code. We might be able to find the offending C library code, given enough time, and perhaps arrange not to call it. A little fragile though.
IIRC, it was a divide that caused an undefined instruction exception. You can run U-Boot w/o the UE_PRIVATE_LIBGCC, and break in w/JTAG and look at the undefined instr shadow regs (sp/lr/pc) and find the opcode that caused the fault pretty easily, again IIRC. But USE_PRIVATE_LIBGCC was intended for just this problem, and works fine.
Tom
Regards, Simon
-- nvpublic
Dear Simon Glass,
In message CAPnjgZ2wCqF2tPWwFUdKG7y_xDeYhbFrEnqXxRJG6eU7yj9Xug@mail.gmail.com you wrote:
The libraries included in the toolchain are built for the ARMv7 CPUs, and hence fail to operate correctly when used by the portion of U-Boot which runs on the ARMv4 CPU, presumably due to ISA differences. IIRC, there are overrides in the U-Boot build process such that some/all of U-Boot is built so it'll run on ARMv4 OK, which is why using libgcc built by U-Boot solves this.
Yes that's right, but actually I have never delved into exactly why. Perhaps it is an integer divide or internal memcpy() call early in the code. We might be able to find the offending C library code, given enough time, and perhaps arrange not to call it. A little fragile though.
That would be the totally wrong approach. Problems should be solved where they originate. Here this appears to be the tool chain, which does not provide a version of libgcc suitable for amv4t configurations.
Best regards,
Wolfgang Denk
Dear Stephen Warren,
In message 4F05D596.6030900@nvidia.com you wrote:
I will accept this only temporarily. Why don't you use a working tool chain instead, or fix the one you are using?
I believe the issue isn't that the toolchain is broken, but due to the mix of multiple CPU types on Tegra, all of which run the same U-Boot binary.
When we can solve this issue with our own version of the libgcc, then we can also solve it by using a tool chain that provides the needed lingcc code.
U-Boot starts execution on the AVP CPU, an ARMv4(?) CPU. U-Boot then inits the main CPUs, ARMv7 Cortex A9s, and arranges for them to continue running U-Boot.
OK, so you have to use a tool chain which provides libgcc code for armv4t systems. What exactly is the problem here?
The libraries included in the toolchain are built for the ARMv7 CPUs,
SO this is not the right tool chain for the job. Ecactly what I said.
and hence fail to operate correctly when used by the portion of U-Boot which runs on the ARMv4 CPU, presumably due to ISA differences. IIRC, there are overrides in the U-Boot build process such that some/all of U-Boot is built so it'll run on ARMv4 OK, which is why using libgcc built by U-Boot solves this.
No, this is NOT a solution, it is a workaround for an inappropriate toolchain. If you want to build code for an armv4t system, you must use a tool chain that supports it.
Best regards,
Wolfgang Denk
On 01/05/2012 12:16 PM, Wolfgang Denk wrote:
In message 4F05D596.6030900@nvidia.com you wrote:
...
The libraries included in the toolchain are built for the ARMv7 CPUs,
SO this is not the right tool chain for the job. Ecactly what I said.
and hence fail to operate correctly when used by the portion of U-Boot which runs on the ARMv4 CPU, presumably due to ISA differences. IIRC, there are overrides in the U-Boot build process such that some/all of U-Boot is built so it'll run on ARMv4 OK, which is why using libgcc built by U-Boot solves this.
No, this is NOT a solution, it is a workaround for an inappropriate toolchain. If you want to build code for an armv4t system, you must use a tool chain that supports it.
But we don't want to generate code for ARMv4 in general, but rather ARMv7 as the toolchain does. Only a tiny part of the code needs to be built for ARMv4, and in general we want to benefit from using ARMv7.
Dear Stephen Warren,
In message 4F05FCBD.2040207@nvidia.com you wrote:
No, this is NOT a solution, it is a workaround for an inappropriate toolchain. If you want to build code for an armv4t system, you must use a tool chain that supports it.
But we don't want to generate code for ARMv4 in general, but rather
Then just turn on the ARMv4 specific options (-march=armv4t -mno-thumb -mthumb-interwork -mtune=arm920t ???) for the files that need it.
But as soon as any of these files liks code from libgcc you have to decide.
ARMv7 as the toolchain does. Only a tiny part of the code needs to be built for ARMv4, and in general we want to benefit from using ARMv7.
Then you should probably still link against a ARMv4 specific libgcc.
If you were building U-Boot's libgcc code with optimization set for ARMv7 this would not fix anything.
Best regards,
Wolfgang Denk
Hi,
On Thu, Jan 5, 2012 at 12:17 PM, Wolfgang Denk wd@denx.de wrote:
Dear Stephen Warren,
In message 4F05FCBD.2040207@nvidia.com you wrote:
No, this is NOT a solution, it is a workaround for an inappropriate toolchain. If you want to build code for an armv4t system, you must use a tool chain that supports it.
But we don't want to generate code for ARMv4 in general, but rather
Then just turn on the ARMv4 specific options (-march=armv4t -mno-thumb -mthumb-interwork -mtune=arm920t ???) for the files that need it.
But as soon as any of these files liks code from libgcc you have to decide.
Perhaps we could adjust Tegra's config.mk to use ARMv4T when not building with the private libgcc?
ARMv7 as the toolchain does. Only a tiny part of the code needs to be built for ARMv4, and in general we want to benefit from using ARMv7.
Then you should probably still link against a ARMv4 specific libgcc.
If you were building U-Boot's libgcc code with optimization set for ARMv7 this would not fix anything.
It might be possible to specify ARMv4T on the link flags and have it pick up the v4T library, even if nearly everything else is ARMv7?
Regards, Simon
Best regards,
Wolfgang Denk
-- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de I'd rather be led to hell than managed to heaven.
On 01/05/2012 01:42 PM, Simon Glass wrote:
Hi,
On Thu, Jan 5, 2012 at 12:17 PM, Wolfgang Denk wd@denx.de wrote:
Dear Stephen Warren,
In message 4F05FCBD.2040207@nvidia.com you wrote:
No, this is NOT a solution, it is a workaround for an inappropriate toolchain. If you want to build code for an armv4t system, you must use a tool chain that supports it.
But we don't want to generate code for ARMv4 in general, but rather
Then just turn on the ARMv4 specific options (-march=armv4t -mno-thumb -mthumb-interwork -mtune=arm920t ???) for the files that need it.
That's exactly what we've already done, but that doesn't affect code that gets pulled in from libgcc, which is what USE_PRIVATE_LIBGCC affects IIUC.
But as soon as any of these files liks code from libgcc you have to decide.
Perhaps we could adjust Tegra's config.mk to use ARMv4T when not building with the private libgcc?
I believe the relevant U-Boot source files are already built for ARMv4T, it's just libgcc that's the issue.
ARMv7 as the toolchain does. Only a tiny part of the code needs to be built for ARMv4, and in general we want to benefit from using ARMv7.
Then you should probably still link against a ARMv4 specific libgcc.
If you were building U-Boot's libgcc code with optimization set for ARMv7 this would not fix anything.
It might be possible to specify ARMv4T on the link flags and have it pick up the v4T library, even if nearly everything else is ARMv7?
I don't think we use any multilib toolchains, so I don't think that's possible.
Dear Stephen,
In message 4F060DD1.9050907@nvidia.com you wrote:
It might be possible to specify ARMv4T on the link flags and have it pick up the v4T library, even if nearly everything else is ARMv7?
I don't think we use any multilib toolchains, so I don't think that's possible.
I don't even think you need one with multilib support. You need one that provides a libgcc for armv4t, that's all.
It is wrong, always and everywhere, NOT to try to fix the problems at the origin. If your tool chain does not meet your requirements, then the first action should always be to get a working tool chain - ideally by getting the deficiencies of the currnt one fixed, or by using another one.
Working around such problems may be a short term approach to get things running quickly. But it appears that more and more people make it a habit to do just that, without even trying to get the real problems fixed upstream. That's bad, bad, bad.
Best regards,
Wolfgang Denk
NVIDIA's flashing tools assume that the bootloader is loaded at address 0x00108000. Instead of requiring non-standard builds of those tools which allow a load address of 0x00E08000, this commit just switches all Tegra2 boards to use the standard load address.
Signed-off-by: Thierry Reding thierry.reding@avionic-design.de Tested-by: Simon Glass sjg@chromium.org --- include/configs/tegra2-common.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/include/configs/tegra2-common.h b/include/configs/tegra2-common.h index e233b1c..f7b6232 100644 --- a/include/configs/tegra2-common.h +++ b/include/configs/tegra2-common.h @@ -152,7 +152,7 @@ #define PHYS_SDRAM_1 TEGRA2_SDRC_CS0 #define PHYS_SDRAM_1_SIZE 0x20000000 /* 512M */
-#define CONFIG_SYS_TEXT_BASE 0x00E08000 +#define CONFIG_SYS_TEXT_BASE 0x00108000 #define CONFIG_SYS_SDRAM_BASE PHYS_SDRAM_1
#define CONFIG_SYS_INIT_RAM_ADDR CONFIG_STACKBASE
On Thu, Nov 17, 2011 at 2:04 AM, Thierry Reding thierry.reding@avionic-design.de wrote:
NVIDIA's flashing tools assume that the bootloader is loaded at address 0x00108000. Instead of requiring non-standard builds of those tools which allow a load address of 0x00E08000, this commit just switches all Tegra2 boards to use the standard load address.
Signed-off-by: Thierry Reding thierry.reding@avionic-design.de Tested-by: Simon Glass sjg@chromium.org
Acked-by: Simon Glass sjg@chromium.org
include/configs/tegra2-common.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/include/configs/tegra2-common.h b/include/configs/tegra2-common.h index e233b1c..f7b6232 100644 --- a/include/configs/tegra2-common.h +++ b/include/configs/tegra2-common.h @@ -152,7 +152,7 @@ #define PHYS_SDRAM_1 TEGRA2_SDRC_CS0 #define PHYS_SDRAM_1_SIZE 0x20000000 /* 512M */
-#define CONFIG_SYS_TEXT_BASE 0x00E08000 +#define CONFIG_SYS_TEXT_BASE 0x00108000 #define CONFIG_SYS_SDRAM_BASE PHYS_SDRAM_1
#define CONFIG_SYS_INIT_RAM_ADDR CONFIG_STACKBASE
1.7.7.3
Thierry Reding wrote at Thursday, November 17, 2011 3:04 AM:
The following series contains two patches that allow mainline U-Boot to boot standalone on Tegra2-based boards. It assumes the standard NVIDIA flashing tools as provided by the Linux4Tegra package. The series is based on patches that have already been reviewed but haven't been merged upstream yet. They are available in patchwork here:
http://patchwork.ozlabs.org/patch/122888 http://patchwork.ozlabs.org/patch/122887 http://patchwork.ozlabs.org/patch/122889 http://patchwork.ozlabs.org/patch/123845 (9 patches)
Thierry Reding (2): tegra2: Always build with USE_PRIVATE_LIBGCC=yes. tegra2: Change CONFIG_SYS_TEXT_BASE to 0x00108000.
The series:
Tested-by: Stephen Warren swarren@nvidia.com Acked-by: Stephen Warren swarren@nvidia.com
(On Seaboard/Springbank, booted a Linux kernel)
Thanks for cleaning this up.
participants (5)
-
Simon Glass -
Stephen Warren -
Thierry Reding -
Tom Warren -
Wolfgang Denk