Re: [PATCH] lguest: PAE support

[Matias Zabaljauregui]

On Sun, 2009-06-07 at 10:58 +0930, Rusty Russell wrote:
> On Sat, 6 Jun 2009 01:39:02 am Matias Zabaljauregui wrote:
> > Hi, this version requires that host and guest have the same PAE status.
> > NX cap is not offered to the guest, yet.
> 
> Thanks, applied!
> 
> I extracted the following parts for moving into your previous "native ops"
> patch:

great, thank you(forgive my laziness)


> diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
> --- a/arch/x86/lguest/boot.c
> +++ b/arch/x86/lguest/boot.c
> @@ -519,7 +519,7 @@ static void lguest_pte_update(struct mm_
>  static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
> pte_t *ptep, pte_t pteval)
>  {
> - *ptep = pteval;
> + native_set_pte(ptep, pteval);
>   lguest_pte_update(mm, addr, ptep);
>  }
>  
> @@ -528,9 +528,9 @@ static void lguest_set_pte_at(struct mm_
>   * changed. */
>  static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
>  {
> - *pmdp = pmdval;
> + native_set_pmd(pmdp, pmdval);
>   lazy_hcall2(LHCALL_SET_PMD, __pa(pmdp) & PAGE_MASK,
> -(__pa(pmdp) & (PAGE_SIZE - 1)) / 4);
> +(__pa(pmdp) & (PAGE_SIZE - 1)) / sizeof(pmd_t));
>  }
>  
>  /* There are a couple of legacy places where the kernel sets a PTE, but we
> @@ -544,7 +544,7 @@ static void lguest_set_pmd(pmd_t *pmdp, 
>   * which brings boot back to 0.25 seconds. */
>  static void lguest_set_pte(pte_t *ptep, pte_t pteval)
>  {
> - *ptep = pteval;
> + native_set_pte(ptep, pteval);
>   if (cr3_changed)
>   lazy_hcall1(LHCALL_FLUSH_TLB, 1);
>  }
> diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
> --- a/drivers/lguest/page_tables.c
> +++ b/drivers/lguest/page_tables.c
> @@ -726,8 +726,9 @@ void map_switcher_in_guest(struct lg_cpu
>* page is already mapped there, we don't have to copy them out
>* again. */
>   pfn = __pa(cpu->regs_page) >> PAGE_SHIFT;
> - regs_pte = pfn_pte(pfn, __pgprot(__PAGE_KERNEL));
> - switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTRS_PER_PTE] = 
> regs_pte;
> + native_set_pte(®s_pte, pfn_pte(pfn, PAGE_KERNEL));
> + native_set_pte(&switcher_pte_page[pte_index((unsigned long)pages)],
> + regs_pte);
>  }
>  /*:*/
>  
> 

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Re: [PATCH 2/4] virtio_net: return NETDEV_TX_BUSY instead of queueing an extra skb.

[Herbert Xu]

On Wed, Jun 03, 2009 at 12:47:04PM +0930, Rusty Russell wrote:
> 
> We could figure out if we can take the worst-case packet, and underutilize
> our queue.  And fix the other *67* drivers.

Most of those are for debugging purposes, i.e., they'll never
happen unless the driver is buggy.

> Of course that doesn't even work, because we return NETDEV_TX_BUSY from dev.c!

If and when your driver becomes part of the core and it has to
feed into other drivers, then you can use this argument :)

> "Hi, core netdevs here.  Don't use NETDEV_TX_BUSY.   Yeah, we can't figure out
> how to avoid it either.  But y'know, just hack something together".

No you've misunderstood my complaint.  I'm not trying to get you
to replace NETDEV_TX_BUSY by the equally abhorrent queue in the
driver, I'm saying that you should stop the queue before you get
a packet that overflows by looking at the amount of free queue
space after transmitting each packet.

For most drivers this is easy to do.  What's so different about
virtio-net that makes this impossible?

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} 
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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