On Wed, Oct 09, 2013 at 03:23:21PM +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2013-10-09 at 14:23 +1100, Michael Ellerman wrote:
> > On Tue, Oct 08, 2013 at 06:46:40PM +1100, Benjamin Herrenschmidt wrote:
> > > With OPALv3, the firmware can provide the address of it's internal console
> > > to Linux, which we can then display using debugfs. This is handy for
> > > diagnostics and debugging.
> > >
> > > Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> > > ---
> > >
> > > diff --git a/arch/powerpc/platforms/powernv/opal.c
> > > b/arch/powerpc/platforms/powernv/opal.c
> > > index 2911abe..10d7894 100644
> > > --- a/arch/powerpc/platforms/powernv/opal.c
> > > +++ b/arch/powerpc/platforms/powernv/opal.c
> > > @@ -17,6 +17,8 @@
> > > #include <linux/interrupt.h>
> > > #include <linux/notifier.h>
> > > #include <linux/slab.h>
> > > +#include <linux/debugfs.h>
> > > +#include <linux/uaccess.h>
> > > #include <asm/opal.h>
> > > #include <asm/firmware.h>
> > >
> > > @@ -27,6 +29,21 @@ struct opal {
> > > u64 entry;
> > > } opal;
> > >
> > > +/* OPAL in-memory console */
> >
> > It might be nice to point out that the format of the struct is defined
> > by OPAL and must be in sync with what OPAL is using.
>
> Yes, we could move the structure definition to opal.h...
>
> > > +struct memcons {
> > > + uint64_t magic;
> >
> > u64 ?
>
> Who cares ?
That's what we use in the kernel. But no I don't care.
> > > +#define MEMCONS_MAGIC 0x6630696567726173
> > > + uint64_t obuf_phys;
> > > + uint64_t ibuf_phys;
> > > + uint32_t obuf_size;
> > > + uint32_t ibuf_size;
> > > + uint32_t out_pos;
> > > +#define MEMCONS_OUT_POS_WRAP 0x80000000u
> > > +#define MEMCONS_OUT_POS_MASK 0x00ffffffu
> >
> > Where does this come from?
>
> My a** :-) I made it up as I wrote the OPAL side one, why ?
...
> > > + uint32_t in_prod;
> > > + uint32_t in_cons;
> > > +};
> >
> > Should it be packed?
>
> Nope, no need. It's all nice and naturally aligned.
Sure, that's obvious.
> > > @@ -369,6 +386,90 @@ static irqreturn_t opal_interrupt(int irq, void
> > > *data)
> > > return IRQ_HANDLED;
> > > }
> > >
> > > +#ifdef CONFIG_DEBUG_FS
> > > +static ssize_t opal_memcons_read(struct file *file, char __user *to,
> > > + size_t count, loff_t *ppos)
> > > +{
> > > + struct memcons *mc = file->private_data;
> > > + size_t available, ret, chunk0, chunk1, lcount;
> > > + const char *start, *conbuf = __va(mc->obuf_phys);
> > > + loff_t opos, pos;
> > > +
> > > + /*
> > > + * Find out how much is in the buffer. If it has wrapped
> > > + * the whole buffer, else just the beginning. It has wrapped
> > > + * if the next character is not \0
> > > + */
> > > + if (mc->out_pos & MEMCONS_OUT_POS_WRAP) {
> > > + available = mc->obuf_size;
> > > + chunk1 = mc->out_pos & MEMCONS_OUT_POS_MASK;
> > > + start = conbuf + chunk1;
> > > + chunk0 = mc->obuf_size - chunk1;
> > > + } else {
> > > + available = mc->out_pos;
> > > + start = conbuf;
> > > + chunk0 = available;
> > > + chunk1 = 0;
> > > + }
> >
> > Surely simple_read_from_buffer() could make some of this simpler?
>
> If you can find a way to make it deal with a ring buffer...
Call it twice.
And you wonder why no one reviews your patches?
cheers
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