Re: [OE-core][PATCH V2] lib32-64k-pagesize.inc: add conf for building 32bit binary with 64K alignment

[ChenQi <Qi.Chen@windriver.com>]

ping

Is there something I need to do for this patch? Or is this patch not 
suitable for oe-core?

Regards,
Qi

On 1/16/25 12:34, Chen Qi via lists.openembedded.org wrote:
> Ping
>
> Ross & Richard, is there anything else I need to do for this patch?
>
> Regards,
> Qi
>
> -----Original Message-----
> From: Chen, Qi
> Sent: Thursday, January 9, 2025 9:54 AM
> To: Ross Burton <Ross.Burton@arm.com>
> Cc: openembedded-core@lists.openembedded.org
> Subject: RE: [OE-core][PATCH V2] lib32-64k-pagesize.inc: add conf for building 32bit binary with 64K alignment
>
> Hi Ross,
>
> The "./bsp/marvell-cn10xxx" exists in yocto-kernel-cache's origin/yocto-6.6 branch.
> In its master branch, the marvell-cn96xx.cfg also enables CONFIG_ARM64_64K_PAGES=y.
>
> This patch was tested on pristine poky + qemuarm64. The test steps are in the commit message. I didn't test all softwares in oe-core, but as lib32-core-image-full-cmdline started well with no failed systemd service, I assumed that most softwares should also behave well. I also tested lib32-sysstat with core-image-minimal.
>
> The help text for ARM64_64K_PAGES changed with this commit: https://github.com/torvalds/linux/commit/db488be354bc85724d7b9523e94435fdaa761a35
> So 32bit arm was not supported at first, but at some point, it was.
>
> Regards,
> Qi
>
> -----Original Message-----
> From: Ross Burton <Ross.Burton@arm.com>
> Sent: Thursday, January 9, 2025 1:02 AM
> To: Chen, Qi <Qi.Chen@windriver.com>
> Cc: openembedded-core@lists.openembedded.org
> Subject: Re: [OE-core][PATCH V2] lib32-64k-pagesize.inc: add conf for building 32bit binary with 64K alignment
>
> On 25 Dec 2024, at 03:04, Chen Qi via lists.openembedded.org <Qi.Chen=windriver.com@lists.openembedded.org> wrote:
>> When 64K page size is enabled, for 32bit multilib, we'll need to build
>> applications with 64K alignment, otherwise, we'll see errors like below at runtime:
>>
>>   root@marvell-cn10xxx:~# /lib/ld-linux-armhf.so.3
>>     Segmentation fault
>>
>> marvell-cn10xxx in yocto-kernel-cache enables CONFIG_ARM64_4K_PAGES=y by default.
>> And the issue was first discovered there.
> Do you mean _64K_PAGES?  Where is this marvell-cn100xxx?  In yocto-kernel-cache there are no users of arm64-64kb-pages and nothing called cn10xxx.  Is this a Wind River-specific fork of yocto-kernel-cache?
>
>> However, there's a kernel config fragment in yocto-kernel-cache which
>> enableds 64K page size for arm64: arch/arm/arm64-64kb-pages.scc. So
>> it's easy for other
>> arm64 BSPs to enable this. And when they do so, they'll have problem
>> with multilib. This patch adds a config file to help people a little
>> bit in such situation.
>>
>> The max-page-size option is used to fix this issue. This option is
>> added to both CFLAGS and LDFLAGS for the purpose of covering as many
>> recipes as possible.
> First, I should point out that changing the page size is an ABI break, and the 32-bit ABI was formalised long before 64kb pages were a thing, so things _will_ break.  That said the loader should work, as a decade ago binutils 2.25 changed the alignment to 64kb pages by default:
>
> https://sourceware.org/git/?p=binutils-gdb.git;a=blobdiff;f=ld/emulparams/armelf_linux.sh;h=280db842208e06e3231ec3a8322369193630a07d;hp=35891f1fc91bddd03677aaefd7146ae5333e6cf0;hb=7572ca8989ead4c3425a1500bc241eaaeffa2c89;hpb=8335d6aa34b88ce31b62e1b578d54ab4aa364435
>
> That won’t help specific pieces of software that eg assume the page size is a built-time constant (and use the wrong constant), but helloworld should be good.  Can you replicate with pristine poky master and a minimal configuration in a qemu?
>
> Ross
>
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