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Subject: Re: [PATCH] x86/sgx: Add SGX_MemTotal to /proc/meminfo
To:     Jarkko Sakkinen <jarkko@kernel.org>, 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
References: <20210818132509.545997-1-jarkko@kernel.org>
From:   Dave Hansen <dave.hansen@intel.com>
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Message-ID: <8e6e42b0-0a1e-6892-b601-ce4a94172ef1@intel.com>
Date:   Mon, 23 Aug 2021 08:15:14 -0700
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In-Reply-To: <20210818132509.545997-1-jarkko@kernel.org>
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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 desktops
> 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.
> 
> Add SGX_MemTotal field to /proc/meminfo, which shows the total amount of
> usable SGX memory in the system.  E.g. with 32 MB reserved for SGX from
> BIOS, the printout would be:
> 
> SGX_MemTotal:      22528 kB

The big question here: Do we want to put purely architecture-specific
entries in (the currently quite arch-independent) /proc/meminfo?

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.