Messages in this thread | | | Date | Fri, 26 Nov 2010 11:29:20 -0800 | From | Andres Salomon <> | Subject | Re: [PATCH v4 resend] OLPC: Add XO-1 suspend/resume support |
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On Fri, 26 Nov 2010 16:28:51 +0000 Daniel Drake <dsd@laptop.org> wrote:
[...] > Re. the printk thing, this was your doing: > http://dev.laptop.org/git/olpc-2.6/commit/?h=stable&id=b4334e9e1444761f19806f9066c6b38ce23079bf [...] > ---------- Forwarded message ---------- > From: Thomas Gleixner <tglx@linutronix.de> > Date: 26 November 2010 09:43 > Subject: Re: [PATCH v4 resend] OLPC: Add XO-1 suspend/resume support > To: Daniel Drake <dsd@laptop.org> > Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org > > > On Thu, 18 Nov 2010, Daniel Drake wrote: > > Feedback after the first submission was quickly acted upon and I > > haven't been able to get a peep since. > > Sorry, fell off the radar. > > > + > > +wakeup_start: > > +# jmp wakeup_start > > Debug leftover ?
Leftovers from the original patch; certainly should be removed.
> > > +asmlinkage int olpc_xo1_do_sleep(u8 sleep_state) > > +{ > > + void *pgd_addr = __va(read_cr3()); > > + printk(KERN_ERR "xo1_do_sleep!\n"); /* this needs to remain > > here so > > + * that gcc doesn't > > optimize > > + * away our __va! */ > > + > > This looks suspect along with the __volatile__ magic below. Care to > explain, what you fear that gcc is optimizing away ? >
I'm working from memory here; in the version of gcc we were using at the time (stock FC5 or FC6), setting pgd_addr immediately followed by the asm below resulted in gcc optimizing away the __va(). The asm turned into simply:
movl %cr3, %eax
With no mention of PAGE_OFFSET. Messing with 'volatile' didn't help. Adding the printk did, as it causes %eax to get clobbered, forcing temporary storage of %cr3 into a separate register. A lot has changed since then (compilers, this code, as well as the definition of read_cr3()), so I highly suspect that it's no longer needed.
> > + /* Enable wakeup through power button */ > > + outl((CS5536_PM_PWRBTN << 16) | 0xFFFF, acpi_base + PM1_STS); > > + > > + __asm__ __volatile__("movl %0,%%eax" : : "r" (pgd_addr)); > > + __asm__("call *(%%edi); cld" > > + : : "D" (&ofw_bios_entry)); > > + __asm__ __volatile__("movb $0x34, %al\n\t" > > + "outb %al, $0x70\n\t" > > + "movb $0x30, %al\n\t" > > + "outb %al, $0x71\n\t"); > > Looks good otherwise. > > Thanks, > > tglx
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