VMWare monitor error on read/modify/write to cr4

VMWare monitor error on read/modify/write to cr4

Post by Zwane Mwaikamb » Thu, 13 Feb 2003 15:00:10

        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");
        clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);


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

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in

More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/


1. Sparcs and atomic read/modify/write operations

I'm writing a device driver for an SBus card whose controller chip
shares with the kernel a number of data structures in main memory.  
For handling a few edge/error conditions, the controller chip
documentation gives the following advise:

        If the host can do a read/modify/write:
                (do something incredibly easy)
                slog through the following hairy pseudocode

Obviously, I'd prefer the former, if possible, but I'm not aware of
the contraints any particular Sun architecture places on me, or
what constructs I'd need to enforce this in my code.  I just
need do an atomic r/m/w of a single 32-bit word in main memory.

Any ideas or pointers to references or sample code?

Steve Dyer

2. 3com 3c905B tx

3. Sockets: write() writes OK, yet read() reads garbage...?

4. DHCP sources

5. monitor device read/writes?

6. netmask

7. Looking for a file read/write monitor utility

8. UFS Performance Enhancements/Limitations

9. Read/write errors with new HP DAT 72 SCSI tape drive

10. Question on writing c program implement cp function using UNIX system calls - read, write, etc.

11. ENOMEM error writing/reading ext3

12. Make zDisk gives me error on boot (Read write)

13. errors reading and writing to fujitsu mo