> -----Original Message----- > From: H. Peter Anvin [mailto:hpa@xxxxxxxxx] > Sent: Friday, April 11, 2014 4:59 PM > To: KY Srinivasan; x86@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx; > apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx; tglx@xxxxxxxxxxxxx; > JBeulich@xxxxxxxx > Subject: Re: [PATCH V1 1/1] X86: Probe for PIC and set legacy_pic > appropriately > > On 04/11/2014 05:50 PM, K. Y. Srinivasan wrote: > > > > + /* > > + * Check to see if we have a PIC. > > + * Mask all except the cascade and read > > + * back the value we just wrote. If we don't > > + * have a PIC, we will read 0xff as opposed to the > > + * value we wrote. > > + */ > > + outb(probe_val, PIC_MASTER_IMR); > > + probe_val = inb(PIC_MASTER_IMR); > > + if (probe_val == 0xff) { > > + printk(KERN_INFO "Using NULL legacy PIC\n"); > > + legacy_pic = &null_legacy_pic; > > + raw_spin_unlock_irqrestore(&i8259A_lock, flags); > > + return; > > + } > > + > > outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ > > outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ > > > > Again, I would do at least the slave masking above the probe. > > Also, I would compare to make sure we get the probe_val back and compare > with != instead of comparing with ==. Will do. Thanks, K. Y _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
