VMWare monitor error on read/modify/write to cr4

From: Zwane Mwaikambo (zwane@holomorphy.com)
Date: Wed Feb 12 2003 - 07:52:03 EST

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Hi,
Current 2.5.60 has code which disables TSC access for tasks
running in lower privelege level than ring0 when disabling kernel TSC
usage. Doing a read, modify, write with only the TSD bit being set causes
it to report a monitor error. This happens before console_init so it hangs
on 'Uncompressing Linux... Ok booting the kernel'

To reproduce, build a 2.5.60 i586+ kernel and boot with notsc.

if (tsc_disable && cpu_has_tsc) {
        printk(KERN_NOTICE "Disabling TSC...\n");
        /**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/
        clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);
        set_in_cr4(X86_CR4_TSD);
}

This isn't a bug report, just an FYI for people using VMWare, and the TSC
in vmware does work.

Zwane

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Next message: Jörn Engel: "[patch] fix missing cfi_cmdset_0020 in drivers/mtd/chips/Makefile"
Previous message: Roger Luethi: "Re: via rhine bug? (timeouts and resets)"
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