Re: [PATCH] lib/xz: remove dead IA-64 (Itanium) support code

Re: [PATCH] lib/xz: remove dead IA-64 (Itanium) support code

[Ankan Biswas]

Hey all,

Correcting the mailing-list again,  from linux-kernel-mentees@kernel.org 
to linux-kernel-mentees@lists.linux.dev.

Really sorry about this.


Thanks,
Ankan

Re: [PATCH] lib/xz: remove dead IA-64 (Itanium) support code

[Lasse Collin]

On 2025-10-13 Ankan Biswas wrote:
> Support for the IA-64 (Itanium) architecture was removed in
> commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture").
> 
> This patch drops the IA-64 specific decompression code from
> lib/xz, which was conditionally compiled with the now-obsolete
> CONFIG_XZ_DEC_IA64 option.

The commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture")
unconditionally disabled the IA-64 filter, which effectively dropped
support for mounting Squashfs file systems that use XZ with the IA-64
filter. I wasn't Cc'ed when it was committed because I wasn't in
MAINTAINERS back then. If I had been, I might have commented that the
commits [1] and [2] and the discussion [3] showed that keeping filters
available for non-native archs can be desirable. But now that time has
passed and no one has complained about the lack of IA-64 filter, it
seems fine to remove it completely from Linux.

I won't remove the IA-64 filter from the upstream version of
xz_dec_bcj.c, so this change will make those files diverge a little
more. That's unfortunate, but they already differ by a tiny amount
anyway.

xz_private.h line 106 checks if XZ_DEC_IA64 is defined. That line
should be removed too. With that change:

    Acked-by: Lasse Collin <lasse.collin@tukaani.org>

[1] 5dc49c75a26b ("decompressors: make the default XZ_DEC_* config
    match the selected architecture")
[2] bf4d064d89ae ("lib/xz: enable all filters by default in Kconfig")
[3] https://lore.kernel.org/lkml/20140228230017.GE14970@merlin.infradead.org/T/

-- 
Lasse Collin

Re: [PATCH] lib/xz: remove dead IA-64 (Itanium) support code

[Ankan Biswas]

On 10/13/25 9:08 PM, Lasse Collin wrote:
> On 2025-10-13 Ankan Biswas wrote:
>> Support for the IA-64 (Itanium) architecture was removed in
>> commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture").
>>
>> This patch drops the IA-64 specific decompression code from
>> lib/xz, which was conditionally compiled with the now-obsolete
>> CONFIG_XZ_DEC_IA64 option.
> 
> The commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture")
> unconditionally disabled the IA-64 filter, which effectively dropped
> support for mounting Squashfs file systems that use XZ with the IA-64
> filter. I wasn't Cc'ed when it was committed because I wasn't in
> MAINTAINERS back then. If I had been, I might have commented that the
> commits [1] and [2] and the discussion [3] showed that keeping filters
> available for non-native archs can be desirable. But now that time has
> passed and no one has complained about the lack of IA-64 filter, it
> seems fine to remove it completely from Linux.
> 
> I won't remove the IA-64 filter from the upstream version of
> xz_dec_bcj.c, so this change will make those files diverge a little
> more. That's unfortunate, but they already differ by a tiny amount
> anyway.
> 
> xz_private.h line 106 checks if XZ_DEC_IA64 is defined. That line
> should be removed too. With that change:
> 
>      Acked-by: Lasse Collin <lasse.collin@tukaani.org>
> 
> [1] 5dc49c75a26b ("decompressors: make the default XZ_DEC_* config
>      match the selected architecture")
> [2] bf4d064d89ae ("lib/xz: enable all filters by default in Kconfig")
> [3] https://lore.kernel.org/lkml/20140228230017.GE14970@merlin.infradead.org/T/
>

Hi Lasse,

I have sent a v2 of the patch with the required changes.
Sorry about having to make your work a little more difficult.

And thanks for retaining support in the upstream for IA-64.


Regards,
Ankan Biswas