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Date:      Fri, 23 Aug 2002 17:08:23 +0200 (CEST)
From:      Martin Blapp <mb@imp.ch>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        Bosko Milekic <bmilekic@unixdaemons.com>, Julian Elischer <julian@elischer.org>, Don Lewis <dl-freebsd@catspoiler.org>, <sos@freebsd.dk>, <marks@ripe.net>, <ktsin@acm.org>, <freebsd-current@FreeBSD.ORG>
Subject:   Re: Memory corruption in CURRENT
Message-ID:  <20020823170045.E50084-100000@levais.imp.ch>
In-Reply-To: <3D6646C8.30E321C5@mindspring.com>

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Hmmmmm,

> Just like Microsoft: they disable the PSE, because they have not
> spent the ~$16,000 worth of time figuring out the root cause.
>
> -- Terry

But what is this ?

+#define X86_CR4_PGE     0x0080  /* enable global pages */
+#define X86_CR4_PCE     0x0100  /* enable performance counters at ipl 3 */
+#define X86_CR4_OSFXSR      0x0200  /* enable fast FPU save and restore */
+#define X86_CR4_OSXMMEXCPT  0x0400  /* enable unmasked SSE exceptions */
+
+/*
+ * Save the cr4 feature set we're using (ie
+ * Pentium 4MB enable and PPro Global page
+ * enable), so that any CPU's that boot up
+ * after us can get the correct flags.
+ */
+extern unsigned long mmu_cr4_features;
+
+static inline void set_in_cr4 (unsigned long mask)
+{
+       mmu_cr4_features |= mask;
+       __asm__("movl %%cr4,%%eax\n\t"
+               "orl %0,%%eax\n\t"
+               "movl %%eax,%%cr4\n"
+               : : "irg" (mask)
+               :"ax");
+}



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