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Message-ID: <e0522fa59b2029d6a2210c1113919b572746f794.camel@kernel.org>
Subject: Re: [PATCH] x86/sgx: Add SGX_MemTotal to /proc/meminfo
From:   Jarkko Sakkinen <jarkko@kernel.org>
To:     Dave Hansen <dave.hansen@intel.com>, linux-sgx@vger.kernel.org
Cc:     Shuah Khan <shuah@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Rapoport <rppt@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Saravanan D <saravanand@fb.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Krish Sadhukhan <krish.sadhukhan@oracle.com>,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org
Date:   Tue, 24 Aug 2021 04:16:11 +0300
In-Reply-To: <8e6e42b0-0a1e-6892-b601-ce4a94172ef1@intel.com>
References: <20210818132509.545997-1-jarkko@kernel.org>
         <8e6e42b0-0a1e-6892-b601-ce4a94172ef1@intel.com>
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On Mon, 2021-08-23 at 08:15 -0700, Dave Hansen wrote:
> On 8/18/21 6:25 AM, Jarkko Sakkinen wrote:
> > The amount of SGX memory on the system is determined by the BIOS and it
> > varies wildly between systems.  It can be from dozens of MB's on deskto=
ps
> > or VM's, up to many GB's on servers.  Just like for regular memory, it =
is
> > sometimes useful to know the amount of usable SGX memory in the system.
> >=20
> > Add SGX_MemTotal field to /proc/meminfo, which shows the total amount o=
f
> > usable SGX memory in the system.  E.g. with 32 MB reserved for SGX from
> > BIOS, the printout would be:
> >=20
> > SGX_MemTotal:      22528 kB
>=20
> The big question here: Do we want to put purely architecture-specific
> entries in (the currently quite arch-independent) /proc/meminfo?
>=20
> The current "DirectMap4k/2M/1G" entries from arch_report_meminfo() are
> arch-specific in their sizes, of course, but the concept is at least
> quite arch-independent.

I started with /proc/meminfo instead of /sys/devices/system/node/*/meminfo
because there is pre-existing arch callback, and secondary because it's als=
o
better fit for my kselftest code.

The same discussion still applies to both files, they probably should follo=
w a
matching pattern.

/Jarkko