linux-kernel - RE: 32bit resctrl? (was Re: [PATCH v2] fs/resctrl: fix domid loss precision issue)

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Message-ID: <SJ1PR11MB6083B9EC479B6B20684FC1C1FC2F2@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Sat, 16 Mar 2024 00:08:12 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>, "Chatre, Reinette"
	<reinette.chatre@...el.com>, Rex Nie <rex.nie@...uarmicro.com>,
	"james.morse@....com" <james.morse@....com>, "x86@...nel.org"
	<x86@...nel.org>, Babu Moger <babu.moger@....com>, Peter Newman
	<peternewman@...gle.com>, Borislav Petkov <bp@...en8.de>
CC: "Yu, Fenghua" <fenghua.yu@...el.com>, "ilpo.jarvinen@...ux.intel.com"
	<ilpo.jarvinen@...ux.intel.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: 32bit resctrl? (was Re: [PATCH v2] fs/resctrl: fix domid loss
 precision issue)

> Why? Making mon_data_bits::u larger in the way it has been done does not
> have any dependency on 32 or 64 builds unless I'm missing something.

That union is copied into the kernfs_node "priv" pointer field. So it has
to fit into whatever size the system is using as a pointer:

See:
	mkdir_mondata_subdir()
		->mon_addfile()

> Caring about 32biit resctrl on x86 is a pointless exercise.

Agree 100%

-Tony