From: David Daney <ddaney@caviumnetworks.com>
To: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: linux-mips@linux-mips.org
Subject: Re: [PATCH v2] Virtual memory size detection for 64 bit MIPS CPUs
Date: Mon, 01 Feb 2010 13:42:53 -0800 [thread overview]
Message-ID: <4B674ADD.1050306@caviumnetworks.com> (raw)
In-Reply-To: <1265058019-21484-1-git-send-email-guenter.roeck@ericsson.com>
Guenter Roeck wrote:
[...]
>
> +static inline void cpu_set_vmbits(struct cpuinfo_mips *c)
> +{
> + if (cpu_has_64bits) {
> + unsigned long zbits;
> +
> + asm volatile(".set mips64\n"
> + "and %0, 0\n"
> + "dsubu %0, 1\n"
> + "dmtc0 %0, $10, 0\n"
> + "dmfc0 %0, $10, 0\n"
> + "dsll %0, %0, 2\n"
> + "dsra %0, %0, 2\n"
> + "dclz %0, %0\n"
> + ".set mips0\n"
> + : "=r" (zbits));
> + c->vmbits = 64 - zbits;
> + } else
> + c->vmbits = 32;
> +}
> +
It should be possible to express this in 'pure' C using
read_c0_entryhi()/write_c0_entryhi(), also you need to be sure you are
not writing 1s to any reserved bits of the register.
David Daney
next prev parent reply other threads:[~2010-02-01 21:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-01 21:00 [PATCH v2] Virtual memory size detection for 64 bit MIPS CPUs Guenter Roeck
2010-02-01 21:42 ` David Daney [this message]
2010-02-01 22:04 ` Guenter Roeck
2010-02-01 22:12 ` David Daney
2010-02-01 22:34 ` Guenter Roeck
2010-02-01 22:39 ` Maciej W. Rozycki
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