[U-Boot-Users] Compiling relocatable code and DATA for PPC
I have been trying to find out right options to configure gcc to produce data and code relocatable code for mpc5xx. The -fpic -meabi -msdata=eabi -G10000 does code as relocatable but data is still absolute. -fpic is incompatible with -msdata=eabi so they can't be used at same time.
based on gcc documentations -msdata=eabi -G10000 should put data so long that it is smaller than valu give in -G option to relative to r2 or r3 but i have not suceeded to do it.
I have been using gcc for producing absolute code for PPC many, many years but now i have need to load dynamically code for non mmu PPC (mpc555). All examples that i have found uses static addresses. Also using google i have not found any answers.
I have tried many forums to find answer but i am still trying to find it. Also i am happy to get pointers to forums/places where i can continue my search.
Kate
In message 40619F6F.40605@iti.fi you wrote:
I have been trying to find out right options to configure gcc to produce data and code
If this is for U-Boot, why don't you just the pre-configured options? They work fine.
relocatable code for mpc5xx. The -fpic -meabi -msdata=eabi -G10000 does code as relocatable but data is still absolute. -fpic is incompatible
This sounds as if you do not understand what relocatable means. Of course relocatable code may use absolute addressing. "relocatable" is different from "position independent".
I have been using gcc for producing absolute code for PPC many, many years but now i have need to load dynamically code for non mmu PPC (mpc555).
What is your environment? U-Boot?
All examples that i have found uses static addresses. Also using google i have not found any answers.
You will either have to use PIC (which is not what U-Boot does), or use a static link address (which is what U-Boot does for standalone applications), or use relocatable code that you can (manually) relocate to a target address of your choice (which is what U-Boot does for the U-Boot code itself).
Best regards,
Wolfgang Denk
Wolfgang Denk wrote:
All examples that i have found uses static addresses. Also using google i have not found any answers.
You will either have to use PIC (which is not what U-Boot does), or use a static link address (which is what U-Boot does for standalone applications), or use relocatable code that you can (manually) relocate to a target address of your choice (which is what U-Boot does for the U-Boot code itself).
The thing that i like to use is PIC and PID ( position independent data and code ). U-boot allows to load my code in any address and i really don't like to manually relocate it. I like to have ready compiled code parts in mass media ( flash ) and i like to to allow load them to any free address.
There is this same problem allways if you use non-mmu processor like MPC555 and you like to load more than just one fixed program into memory. You should remember that the applications loaded with u-boot are not allways just "stand-alone" apps or Linux. Based on my knowledge there is not even Linux for mpc555. I our case i like to load my open source rtos kernel ( Katix ) and then applications for it.
Becouse u-boot runs in many non-mmu processors i was just thinking that some u-boot user has had same problem and find already answer.
I have searched all around internet to find answer but not yet find one. -fpic should make program code position independent and -msdata=eabi -G20000 should put all static data smaller than 20000 bytes to relative to r2(const data) or r13 . For some reason gcc says that -msdata=eabi and -fpic are incompatible and even -msdata=eabi does not make data references as register relative.
Kate
participants (2)
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Kate Alhola -
Wolfgang Denk