Re: AMD FX CPU bug, not fixed by latest microcode?

[Boszormenyi Zoltan]

2012-06-11 09:52 keltezéssel, Clemens Ladisch írta:
> Boszormenyi Zoltan wrote:
> > I have an AMD FX-8120 boxed CPU in an ASUS M5A99X-EVO mainboard
> > with 32GB DDR3/1600 memory, running Fedora 17, upgraded from 16.
> >
> > I get occasional crashes and signal 11 during kernel compilation even
> > with single-job make. Sometimes the compiler jumps out with a strange
> > error message, like "stray \NNN character in the source". When re-running
> > make, the error doesn't happen in the same file and the source file doesn't
> > contain the character being complained about when inspecting with
> > an editor or hexdump.
> >
> > Now, a few minutes ago I was able to catch this bug when I copied the
> > kernel GIT tree to apply a patch manually and did "git commit -a".
> > Strangely, the commit contained one extra file that I didn't touch.
> > git diff showed this for the extra file:
> >
> > ==============================
> > --- a/drivers/usb/gadget/fsl_usb2_udc.h
> > +++ b/drivers/usb/gadget/fsl_usb2_udc.h
> > @@ -427,7 +427,7 @@ struct ep_td_struct {
> >   #define  DTD_ADDR_MASK                        0xFFFFFFE0
> >   #define  DTD_PACKET_SIZE                      0x7FFF0000
> >   #define  DTD_LENGTH_BIT_POS                   16
> > -#define  DTD_ERROR_MASK                       (DTD_STATUS_HALTED | \
> > +#define  DTD_ERROR_MASK                       (DTD_STATUS_HALTED | ^Z
> >                                                  DTD_STATUS_DATA_BUFF_ERR | \
> >                                                  DTD_STATUS_TRANSACTION_ERR)
> >   /* Alignment requirements; must be a power of two */
> > ==============================
> >
> > The "^Z" is a 0-character in the file and is not present in the
> > original source tree, only in the copy.

Actually, the "^Z" there is 0x1a. It should be 0x5c, the backslash character.

> Is it always a zero, or other invalids characters?
> (The (number of) changed bits might tell something.)

IIRC, GCC has a different error for a 0-character and "stray \NNN character"
(that's not inside a string literal) and both happened at some time.
Sorry, I didn't bother to make a note of the error messages.

> > Similar errors happened during copying large files on the same
> > machine but it seems it's enough to trigger if the total amount
> > of data read is large enough.
> Does "large enough" mean "large enough so that they are not in the file
> cache"?
>
> All caches and your memory are ECC protected,

Unfortunately the memory is not with ECC. "Large enough" means it's
usually not in file system cache

>   so I think it is unlikely
> that the problem is with these.  If I had to guess, I'd point to your
> disk (firmware) or the SATA controller.  (A bad or loose SATA cable
> would throw CRC errors into the kernel log.  Are there any?)

The disks (8 of them) are attached to 3ware 9650SE-8LPML in RAID10.
tw_cli reports no problems.

> What is the exact offset of the changed byte in the file?  (It might be
> at a cacheline, sector, or page boundary.)

The bad character is at offset 0x4b74.

> > Does anyone know whether it's a known problem in AMD FX CPUs?
> http://support.amd.com/us/Processor_TechDocs/48063_15h_Mod_00h-0Fh_Rev_Guide.pdf

Thanks but I have seen this file already. The "no fix planned" for every
errata is saddening...

> Regards,
> Clemens

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