libfdt: Add option to disable arch_fixup_fdt() calls

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

---

  Kconfig                  | 8 ++++++++
  arch/arm/lib/bootm-fdt.c | 2 ++
  common/image-fdt.c       | 3 +++
  3 files changed, 13 insertions(+)

Kconfig +8 -0

index 4b4621666560..3efba624ecff 100644
@@ -291,6 +291,14 @@ config SYS_CLK_FREQ
  	help
  	  TODO: Move CONFIG_SYS_CLK_FREQ for all the architecture
 
+config DISABLE_ARCH_FIXUP_FDT
+	bool "Disable arch_fixup_fdt() call"
+	depends on ARM
+	help
+	  Disable FDT memory map syncup before OS boot. This feature can be
+	  used for booting OS with different memory setup where the part of
+	  the memory location should be used for different purpose.
+
  endmenu		# Boot images
 
  source "common/Kconfig"

arch/arm/lib/bootm-fdt.c +2 -0

index 7677358742e1..a873b778ade9 100644
@@ -24,6 +24,7 @@
 
  DECLARE_GLOBAL_DATA_PTR;
 
+#ifndef CONFIG_DISABLE_ARCH_FIXUP_FDT
  int arch_fixup_fdt(void *blob)
  {
  	bd_t *bd = gd->bd;

@@ -50,3 +51,4 @@ int arch_fixup_fdt(void *blob)
  #endif
  	return ret;
  }
+#endif

common/image-fdt.c +3 -0

index 6cac7dbb7f8b..9e05becd464a 100644
@@ -460,6 +460,9 @@ __weak int ft_verify_fdt(void *fdt)
 
  __weak int arch_fixup_fdt(void *blob)
  {
+#ifdef CONFIG_DISABLE_ARCH_FIXUP_FDT
+	printf("## Disable arch_fixup_fdt()\n");
+#endif
  	return 0;
  }
 

Quoted 6 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Quoted 6 lines · Alexander Graf

Quoted 5 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Quoted 3 lines

Quoted 1 line

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Not sure what exactly you are asking for.
Do you mean to add fixup function to board file and overwrite default one?

Quoted 10 lines · Michal Simek

Quoted 9 lines · Alexander Graf

Quoted 6 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Quoted 3 lines

Not sure what exactly you are asking for.
Do you mean to add fixup function to board file and overwrite default one?

You have to touch some other code anyway to make this work with a particular board, right? In that case, you can as well add a function to the board file that explicitly provides a different, known good memory map.

Can you have a weaker overload? Basically I would like to have a board provide arch_fixup_fdt() which would override the one in bootm-fdt.c. But we can also rename arch_fixup_fdt() in bootm-fdt.c to board_fixup_fdt() function, declare it weak and have arch_fixup_fdt() call that.

Quoted 11 lines · Alexander Graf

Quoted 10 lines · Michal Simek

Quoted 9 lines · Alexander Graf

Quoted 6 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Quoted 7 lines

Quoted 3 lines

Not sure what exactly you are asking for.
Do you mean to add fixup function to board file and overwrite default one?

You have to touch some other code anyway to make this work with a particular board, right? In that case, you can as well add a function to the board file that explicitly provides a different, known good memory map.

I cant' see the reason to touch particular board. In past AMP solution where one core use the part of memory and second another part was the reason I needed this.
For ARM64 case as you know from arm IRC I was trying to boot Linux from memory above 32bit space and for these tests I need to convince u-boot not to touch dtb memory setup.

But for the same board I want to use standard behavior but for some case this needs to be enabled.

Quoted 27 lines · Michal Simek

Quoted 11 lines · Alexander Graf

Quoted 10 lines · Michal Simek

Quoted 9 lines · Alexander Graf

Quoted 6 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Quoted 7 lines

Quoted 3 lines

Not sure what exactly you are asking for.
Do you mean to add fixup function to board file and overwrite default one?

You have to touch some other code anyway to make this work with a particular board, right? In that case, you can as well add a function to the board file that explicitly provides a different, known good memory map.

I cant' see the reason to touch particular board. In past AMP solution where one core use the part of memory and second another part was the reason I needed this.
For ARM64 case as you know from arm IRC I was trying to boot Linux from memory above 32bit space and for these tests I need to convince u-boot not to touch dtb memory setup.

Quoted 2 lines

But for the same board I want to use standard behavior but for some case this needs to be enabled.

For that particular case, can you try to see whether you can convince U-Boot to just run in high memory instead? That would make things much more consistent IMHO.

Giving U-Boot and Linux different views of the memory map is really just asking for trouble. You'd have to make sure that you flush your caches for example so that Linux doesn't suddenly get memory overwritten from stale cache entries on the low memory even though Linux is already accessing the high addresses.

For testing, sure, but to actually make use of it I'd rather see a clean solution.

Quoted 37 lines · Alexander Graf

Quoted 27 lines · Michal Simek

Quoted 11 lines · Alexander Graf

Quoted 10 lines · Michal Simek

Quoted 9 lines · Alexander Graf

Quoted 6 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Quoted 7 lines

Quoted 3 lines

Not sure what exactly you are asking for.
Do you mean to add fixup function to board file and overwrite default one?

You have to touch some other code anyway to make this work with a particular board, right? In that case, you can as well add a function to the board file that explicitly provides a different, known good memory map.

I cant' see the reason to touch particular board. In past AMP solution where one core use the part of memory and second another part was the reason I needed this.
For ARM64 case as you know from arm IRC I was trying to boot Linux from memory above 32bit space and for these tests I need to convince u-boot not to touch dtb memory setup.

Quoted 2 lines

But for the same board I want to use standard behavior but for some case this needs to be enabled.

For that particular case, can you try to see whether you can convince U-Boot to just run in high memory instead? That would make things much more consistent IMHO.

Quoted 5 lines

Giving U-Boot and Linux different views of the memory map is really just asking for trouble. You'd have to make sure that you flush your caches for example so that Linux doesn't suddenly get memory overwritten from stale cache entries on the low memory even though Linux is already accessing the high addresses.

For systems where you have one main memory and standard usage model with OS I agree that having this option enabled is bring more problems. But for our use cases you can add memory controller to PL and it will be ready when bitstream is loaded which can be done after u-boot is loaded. It means u-boot have to work with different memory setup then Linux later on.

Caches should be flushed before u-boot pass control to Linux that's why there shouldn't be any stale entries.

For ZynqMP you can partitioned memory that part of it goes to A53s and part to R5s and u-boot is capable to boot both cores.

Quoted 2 lines

For testing, sure, but to actually make use of it I'd rather see a clean solution.

Do we have any experimental Kconfig entry which I can use for it?

Quoted 44 lines · Michal Simek

Quoted 37 lines · Alexander Graf

Quoted 27 lines · Michal Simek

Quoted 11 lines · Alexander Graf

Quoted 10 lines · Michal Simek

Quoted 9 lines · Alexander Graf

Quoted 6 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Quoted 7 lines

Quoted 3 lines

Not sure what exactly you are asking for.
Do you mean to add fixup function to board file and overwrite default one?

You have to touch some other code anyway to make this work with a particular board, right? In that case, you can as well add a function to the board file that explicitly provides a different, known good memory map.

I cant' see the reason to touch particular board. In past AMP solution where one core use the part of memory and second another part was the reason I needed this.
For ARM64 case as you know from arm IRC I was trying to boot Linux from memory above 32bit space and for these tests I need to convince u-boot not to touch dtb memory setup.

Quoted 2 lines

But for the same board I want to use standard behavior but for some case this needs to be enabled.

For that particular case, can you try to see whether you can convince U-Boot to just run in high memory instead? That would make things much more consistent IMHO.

Quoted 5 lines

Giving U-Boot and Linux different views of the memory map is really just asking for trouble. You'd have to make sure that you flush your caches for example so that Linux doesn't suddenly get memory overwritten from stale cache entries on the low memory even though Linux is already accessing the high addresses.

Quoted 6 lines

For systems where you have one main memory and standard usage model with OS I agree that having this option enabled is bring more problems. But for our use cases you can add memory controller to PL and it will be ready when bitstream is loaded which can be done after u-boot is loaded. It means u-boot have to work with different memory setup then Linux later on.

Oh, I see. So U-Boot actually uses completely different memory? But that means that the original memory is also still there, doesn't it? Wouldn't that mean we'd merely have to extend the bdinfo?

Quoted 6 lines

Caches should be flushed before u-boot pass control to Linux that's why there shouldn't be any stale entries.

For ZynqMP you can partitioned memory that part of it goes to A53s and part to R5s and u-boot is capable to boot both cores.

Hm, maybe I'm not fully grasping the exact scenario you're envisioning.

Quoted 5 lines

Quoted 3 lines

For testing, sure, but to actually make use of it I'd rather see a clean solution.

Do we have any experimental Kconfig entry which I can use for it?

Uh, the patch you posted I guess. Just make sure people don't set it if they don't know *exactly* what they're getting themselves into.

Quoted 54 lines · Alexander Graf

Quoted 44 lines · Michal Simek

Quoted 37 lines · Alexander Graf

Quoted 27 lines · Michal Simek

Quoted 11 lines · Alexander Graf

Quoted 10 lines · Michal Simek

Quoted 9 lines · Alexander Graf

Quoted 6 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

Could we instead just have the board file provide a fixup? It could then also fix up the efi memory map.

Quoted 7 lines

Quoted 3 lines

Not sure what exactly you are asking for.
Do you mean to add fixup function to board file and overwrite default one?

You have to touch some other code anyway to make this work with a particular board, right? In that case, you can as well add a function to the board file that explicitly provides a different, known good memory map.

I cant' see the reason to touch particular board. In past AMP solution where one core use the part of memory and second another part was the reason I needed this.
For ARM64 case as you know from arm IRC I was trying to boot Linux from memory above 32bit space and for these tests I need to convince u-boot not to touch dtb memory setup.

Quoted 2 lines

But for the same board I want to use standard behavior but for some case this needs to be enabled.

For that particular case, can you try to see whether you can convince U-Boot to just run in high memory instead? That would make things much more consistent IMHO.

Quoted 5 lines

Giving U-Boot and Linux different views of the memory map is really just asking for trouble. You'd have to make sure that you flush your caches for example so that Linux doesn't suddenly get memory overwritten from stale cache entries on the low memory even though Linux is already accessing the high addresses.

Quoted 6 lines

For systems where you have one main memory and standard usage model with OS I agree that having this option enabled is bring more problems. But for our use cases you can add memory controller to PL and it will be ready when bitstream is loaded which can be done after u-boot is loaded. It means u-boot have to work with different memory setup then Linux later on.

Quoted 3 lines

Oh, I see. So U-Boot actually uses completely different memory? But that means that the original memory is also still there, doesn't it? Wouldn't that mean we'd merely have to extend the bdinfo?

It can be completely different memory or just part can be shared. Depends on use case.
Also you can run just SW on particular core/cores.

I don't think that there is need for bootloader to know all stuff about system. For me bootloader is here to help me to bring my app (or better OS with APP) how I like.
And doing smart stuff is good but not for complicated cases that's why I would like to have a button to disable it.

I can imagine for zcu102 which you also have to read SPD from memory and based on that setup memory sizes and push this setting to OS as very useful but running this standard OS style is just one particular use case. R5s on the chip + the whole PL with possible cpus there requires different behavior.

Quoted 8 lines

Quoted 6 lines

Caches should be flushed before u-boot pass control to Linux that's why there shouldn't be any stale entries.

For ZynqMP you can partitioned memory that part of it goes to A53s and part to R5s and u-boot is capable to boot both cores.

Hm, maybe I'm not fully grasping the exact scenario you're envisioning.

:-)

Quoted 4 lines

Quoted 4 lines

Quoted 3 lines

For testing, sure, but to actually make use of it I'd rather see a clean solution.

Quoted 4 lines

Quoted 1 line

Do we have any experimental Kconfig entry which I can use for it?

Uh, the patch you posted I guess. Just make sure people don't set it if they don't know *exactly* what they're getting themselves into.

It is not enabled by default but I am happy to add any other more advance dependency.

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

---

 Kconfig                  | 8 ++++++++
 arch/arm/lib/bootm-fdt.c | 2 ++
 common/image-fdt.c       | 3 +++
 3 files changed, 13 insertions(+)

Kconfig +0 -0

index 4b4621666560..3efba624ecff 100644
@@ -291,6 +291,14 @@ config SYS_CLK_FREQ
        help
          TODO: Move CONFIG_SYS_CLK_FREQ for all the architecture
 

Kconfig +0 -0

 source "common/Kconfig"

arch/arm/lib/bootm-fdt.c +2 -0

index 7677358742e1..a873b778ade9 100644
@@ -24,6 +24,7 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#ifndef CONFIG_DISABLE_ARCH_FIXUP_FDT
 int arch_fixup_fdt(void *blob)
 {
        bd_t *bd = gd->bd;

@@ -50,3 +51,4 @@ int arch_fixup_fdt(void *blob)
 #endif
        return ret;
 }
+#endif

common/image-fdt.c +3 -1

index 6cac7dbb7f8b..9e05becd464a 100644
@@ -460,6 +460,9 @@ __weak int ft_verify_fdt(void *fdt)
 
 __weak int arch_fixup_fdt(void *blob)
 {
+#ifdef CONFIG_DISABLE_ARCH_FIXUP_FDT
+       printf("## Disable arch_fixup_fdt()\n");
+#endif
        return 0;
 }
 
--

1.9.1

Hi Michal,

Quoted 21 lines · Michal Simek

Disable arch_fixup_fdt() calls for cases where U-Boot shouldn't update memory setup in DTB file.
One example of usage of this option is to boot OS with different memory setup than U-Boot use.

Signed-off-by Michal Simek <[email protected]>

---

 Kconfig                  | 8 ++++++++
 arch/arm/lib/bootm-fdt.c | 2 ++
 common/image-fdt.c       | 3 +++
 3 files changed, 13 insertions(+)

Kconfig +0 -0

index 4b4621666560..3efba624ecff 100644
@@ -291,6 +291,14 @@ config SYS_CLK_FREQ
        help
          TODO: Move CONFIG_SYS_CLK_FREQ for all the architecture
 

Kconfig config SYS_CLK_FREQ · line 303

Quoted 10 lines

Kconfig +8 -0

+config DISABLE_ARCH_FIXUP_FDT
+       bool "Disable arch_fixup_fdt() call"
+       depends on ARM
+       help
+         Disable FDT memory map syncup before OS boot. This feature can be
+         used for booting OS with different memory setup where the part of
+         the memory location should be used for different purpose.
+
 endmenu                # Boot images
 

I think this would be better as a positive Kconfig - ARCH_FIXUP_FDT.

Also this is pretty ugly - with a weak function that gets #ifdefed out. How about changing it so that the function is only called if the Kconfig is set, and then it does not have to be weak?