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    SubjectRe: [PATCH] Add TAINT_HARDWARE_UNSUPPORTED flag
    On Thu, 17 Jun 2010 15:54:09 -0400
    Prarit Bhargava <prarit@redhat.com> wrote:

    >
    > This patch is similar to Theordore Ts'o's TAINT_USER patch,
    > linux-2.6 commit 34f5a39899f3f3e815da64f48ddb72942d86c366.
    >
    > Individual distributions may enable "generic" features such as X86 support,
    > PPC support, and driver support.
    >
    > Some of the features that are enabled by these "generic" feature flags may
    > not be considered supported by the individual distribution.
    >
    > For example, a distribution may want to support PPC but not the Power5
    > chipset, or the e1000e driver but not a card with a specific DeviceID because
    > of known firmware issues.
    >
    > Typically, one would push a config patch to enable and disable the feature and
    > patch the distribution. However, in some cases this is not feasible in order
    > to preserve kabi and at the same time maintain parity with the upstream kernel.
    > In some cases the distribution may want to allow booting of these features but
    > explicitly notify a user that they are not "officially" supported. It is also
    > possible that the hardware is fixed via a firmware update at a later date,
    > making it supported again.
    >
    > It would be useful for a distribution to notify the installer and
    > bug reporting applications, and notify users that the hardware they are using
    > is unsupported during panic, oops, BUG(), and WARN().
    >
    > This patch introduces the TAINT_HARDWARE_UNSUPPORTED flag for distributions
    > to use.
    >
    > Signed-off-by: Prarit Bhargava <prarit@redhat.com>
    > Signed-off-by: Don Zickus <dzickus@redhat.com>
    >
    > diff --git a/Documentation/oops-tracing.txt b/Documentation/oops-tracing.txt
    > index 6fe9001..e337b0a 100644
    > --- a/Documentation/oops-tracing.txt
    > +++ b/Documentation/oops-tracing.txt
    > @@ -263,6 +263,8 @@ characters, each representing a particular tainted value.
    > 12: 'I' if the kernel is working around a severe bug in the platform
    > firmware (BIOS or similar).
    >
    > + 13: 'H' if the hardware is unsupported by the distribution
    > +
    > The primary reason for the 'Tainted: ' string is to tell kernel
    > debuggers if this is a clean kernel or if anything unusual has
    > occurred. Tainting is permanent: even if an offending module is
    > diff --git a/include/linux/kernel.h b/include/linux/kernel.h
    > index 8317ec4..f722b0d 100644
    > --- a/include/linux/kernel.h
    > +++ b/include/linux/kernel.h
    > @@ -347,6 +347,7 @@ extern enum system_states {
    > #define TAINT_WARN 9
    > #define TAINT_CRAP 10
    > #define TAINT_FIRMWARE_WORKAROUND 11
    > +#define TAINT_HARDWARE_UNSUPPORTED 12
    >
    > extern void dump_stack(void) __cold;
    >
    > diff --git a/kernel/panic.c b/kernel/panic.c
    > index 3b16cd9..8d081ff 100644
    > --- a/kernel/panic.c
    > +++ b/kernel/panic.c
    > @@ -180,6 +180,7 @@ static const struct tnt tnts[] = {
    > { TAINT_WARN, 'W', ' ' },
    > { TAINT_CRAP, 'C', ' ' },
    > { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
    > + { TAINT_HARDWARE_UNSUPPORTED, 'H', ' ' },
    > };
    >
    > /**
    > @@ -197,6 +198,7 @@ static const struct tnt tnts[] = {
    > * 'W' - Taint on warning.
    > * 'C' - modules from drivers/staging are loaded.
    > * 'I' - Working around severe firmware bug.
    > + * 'H' - Hardware is unsupported.
    > *
    > * The string is overwritten by the next call to print_tainted().
    > */
    > @@ -243,6 +245,9 @@ void add_taint(unsigned flag)
    > */
    > if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
    > printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
    > + if (flag == TAINT_HARDWARE_UNSUPPORTED)
    > + printk(KERN_CRIT
    > + "WARNING: This system's hardware is unsupported.\n");
    >
    > set_bit(flag, &tainted_mask);
    > }

    That's pretty user-hostile. What are they to do - throw the entire
    computer away because it has the wrong type of mouse?

    How about

    void add_hardware_unsupported_taint(const char *hardware)
    {
    printk(KERN_CRIT
    "Hardware device %s is unsupported by this kernel's vendor\n",
    hardware);
    add_taint(TAINT_HARDWARE_UNSUPPORTED);
    }

    and

    /*
    * Don't call add_taint(TAINT_HARDWARE_UNSUPPORTED) directly - use
    * add_hardware_unsupported_taint()
    */
    #define TAINT_HARDWARE_UNSUPPORTED 12



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