some question about aarch32 for ARM64

loody

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Feb 23, 2015, 7:30:11 AM2/23/15

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hi all:
I follow below instructions to compile a simple c file as aarch32 but in vain.

https://gcc.gnu.org/onlinedocs/gcc-4.9.1/gcc/AArch64-Options.html#AArch64-Options

And I download the toolchain from
http://www.linaro.org/downloads/
(linaro-toolchain-binaries 4.9 (Aarch64 little-endian))

I saw there are aarch32 support in arm64 kernel porting.
Would you mind to let us know how to get aarch32 ELF for running on
ARM64 processors?

Sincerely appreciate your kind help in advance,

PS:Below is my compile error message:
#aarch64-linux-gnu-gcc -mabi=ilp32 test.c
/media/sdb2/toolchain/arm/gcc-
linaro-aarch64-linux-gnu-4.9-2014.09_linux/bin/../lib/gcc/aarch64-linux-gnu/4.9.2/../../../../aarch64-linux-gnu/bin/ld:
skipping incompatible
/media/sdb2/toolchain/arm/gcc-linaro-aarch64-linux-gnu-4.9-2014.09_linux/bin/../lib/gcc/aarch64-linux-gnu/4.9.2/libgcc.a
when searching for -lgcc

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Catalin Marinas

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Feb 23, 2015, 8:30:07 AM2/23/15

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On Mon, Feb 23, 2015 at 12:28:57PM +0000, loody wrote:
> I follow below instructions to compile a simple c file as aarch32 but in vain.
>
> https://gcc.gnu.org/onlinedocs/gcc-4.9.1/gcc/AArch64-Options.html#AArch64-Options

On the above link, there are no instructions on how to compile an
AArch32 application with the AArch64 compiler. You need an AArch32 gcc
(e.g. arm-linux-gnu-gcc, not aarch64-linux-gnu-gcc).

> I saw there are aarch32 support in arm64 kernel porting.

Yes, that's to support AArch32 binaries (ARMv8/v7/...).

> Would you mind to let us know how to get aarch32 ELF for running on
> ARM64 processors?

Just use the right compiler.

> PS:Below is my compile error message:
> #aarch64-linux-gnu-gcc -mabi=ilp32 test.c

-mabi=ilp32 is entirely different from an AArch32 compiler. The above
still generates AArch64 but with the ILP32 ABI (sizeof int/long/pointer
is 32-bit).

--
Catalin

loody

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Feb 24, 2015, 12:20:06 AM2/24/15

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hi catalin:

2015-02-23 21:27 GMT+08:00 Catalin Marinas <catalin...@arm.com>:
> On Mon, Feb 23, 2015 at 12:28:57PM +0000, loody wrote:
>> I follow below instructions to compile a simple c file as aarch32 but in vain.
>>
>> https://gcc.gnu.org/onlinedocs/gcc-4.9.1/gcc/AArch64-Options.html#AArch64-Options
>
> On the above link, there are no instructions on how to compile an
> AArch32 application with the AArch64 compiler. You need an AArch32 gcc
> (e.g. arm-linux-gnu-gcc, not aarch64-linux-gnu-gcc).
>
>> I saw there are aarch32 support in arm64 kernel porting.
>
> Yes, that's to support AArch32 binaries (ARMv8/v7/...).
>
>> Would you mind to let us know how to get aarch32 ELF for running on
>> ARM64 processors?
>
> Just use the right compiler.
>
>> PS:Below is my compile error message:
>> #aarch64-linux-gnu-gcc -mabi=ilp32 test.c
>
> -mabi=ilp32 is entirely different from an AArch32 compiler. The above
> still generates AArch64 but with the ILP32 ABI (sizeof int/long/pointer
> is 32-bit).

so per your explanation, AArch32 binary could be created by any
arm-linux-gnu-gcc which support armv7 and previous instructions.
And -mabi=ilp32 is still aarch64 but with ILP32 ABI.
appreciate your kind help ^^

Jon Masters

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Mar 16, 2015, 6:50:07 AM3/16/15

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On 2/24/15, 12:19 AM, loody wrote:

>>> PS:Below is my compile error message:
>>> #aarch64-linux-gnu-gcc -mabi=ilp32 test.c
>>
>> -mabi=ilp32 is entirely different from an AArch32 compiler. The above
>> still generates AArch64 but with the ILP32 ABI (sizeof int/long/pointer
>> is 32-bit).
> so per your explanation, AArch32 binary could be created by any
> arm-linux-gnu-gcc which support armv7 and previous instructions.
> And -mabi=ilp32 is still aarch64 but with ILP32 ABI.
> appreciate your kind help ^^

This is the correct summary.

Jon.