From: olof@lixom•net (Olof Johansson)
To: Luke Browning <lukebr@linux•vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba•org>,
cbe-oss-dev@ozlabs•org, Arnd Bergmann <arnd@arndb•de>,
linuxppc-dev@ozlabs•org
Subject: Re: [PATCH v2] powerpc: 64K page support for kexec
Date: Thu, 26 Apr 2007 02:15:32 -0500 [thread overview]
Message-ID: <20070426071532.GA24937@lixom.net> (raw)
In-Reply-To: <1177529739.24866.34.camel@luke-laptop>
Hi,
Two comments below, besides that it looks good!
On Wed, Apr 25, 2007 at 04:35:39PM -0300, Luke Browning wrote:
> +#define LP_SHIFT 12
> +#define LP_BITS 8
> +#define LP_MASK(i) ((0xFF >> (i)) << LP_SHIFT)
> +
> +static void hpte_decode(hpte_t *hpte, unsigned long slot,
> + int *psize, unsigned long *va)
> +{
> + unsigned long hpte_r = hpte->r;
> + unsigned long hpte_v = hpte->v;
> + unsigned long avpn;
> + int i, size, shift, penc, avpnm_bits;
> +
> + if (!(hpte_v & HPTE_V_LARGE))
> + size = MMU_PAGE_4K;
> + else {
> + for (i = 0; i < LP_BITS; i++) {
> + if ((hpte_r & LP_MASK(i+1)) == LP_MASK(i+1))
> + break;
> + }
> + penc = LP_MASK(i+1) >> LP_SHIFT;
> + for (size = 0; size < MMU_PAGE_COUNT - 1; size++) {
This will never consider the last page size. Either <= MMU_PAGE_COUNT-1
or < MMU_PAGE_COUNT. The latter would be more natural.
> - pteg = slot / HPTES_PER_GROUP;
> - if (hpte_v & HPTE_V_SECONDARY)
> - pteg = ~pteg;
> + /* 4K pages are not represented by LP */
> + if (size == MMU_PAGE_4K)
> + continue;
> +
> + /* valid entries have a shift value */
> + if (!mmu_psize_defs[size].shift)
> + continue;
>
> - vpi = ((va >> 28) ^ pteg) & htab_hash_mask;
> + if (penc == mmu_psize_defs[size].penc)
> + break;
> + }
> + }
>
> - va |= vpi << PAGE_SHIFT;
> + /*
> + * FIXME, the code below works for 16M, 64K, and 4K pages as these
> + * fall under the p<=23 rules for calculating the virtual address.
> + * In the case of 16M pages, an extra bit is stolen from the AVPN
> + * field to achieve the requisite 24 bits.
> + *
> + * 16G pages are not supported by the code below.
> + */
> + BUG_ON(hpte_v & 0x4000000000000000UL); /* 1T segment */
> + BUG_ON(size == MMU_PAGE_16G);
> + BUG_ON(size == MMU_PAGE_64K_AP);
Milton didn't like BUG_ON() here, and I think I agree after hearing his
motivations. I know I was the one suggesting them, but they're better
to keep out at the moment.
[...]
Thanks,
-Olof
next prev parent reply other threads:[~2007-04-26 7:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-24 18:31 [PATCH] 64K page support for kexec Luke Browning
2007-04-24 19:43 ` Olof Johansson
2007-04-24 22:50 ` Benjamin Herrenschmidt
2007-04-24 23:07 ` Olof Johansson
2007-04-25 5:48 ` Milton Miller
2007-04-25 19:35 ` [PATCH v2] powerpc: " Luke Browning
2007-04-25 22:19 ` Benjamin Herrenschmidt
2007-04-26 15:28 ` Luke Browning
2007-04-27 4:36 ` [PATCH v3] " Milton Miller
2007-04-27 14:42 ` Luke Browning
2007-04-27 16:51 ` Milton Miller
2007-04-27 16:22 ` [PATCH v4] " Luke Browning
2007-04-27 16:59 ` Milton Miller
2007-04-27 17:30 ` Luke Browning
2007-04-27 18:23 ` Haren Myneni
2007-04-29 5:35 ` Milton Miller
2007-04-29 8:30 ` Paul Mackerras
2007-04-29 9:31 ` Benjamin Herrenschmidt
2007-04-29 13:27 ` Segher Boessenkool
2007-04-29 22:49 ` Benjamin Herrenschmidt
2007-04-26 7:15 ` Olof Johansson [this message]
2007-04-24 22:48 ` [PATCH] " Benjamin Herrenschmidt
2007-04-25 13:06 ` Luke Browning
2007-04-25 22:11 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2007-04-26 22:23 [PATCH v3] powerpc: " Luke Browning
2007-04-26 22:32 ` Olof Johansson
2007-05-02 14:19 ` [PATCH v4] " Luke Browning
2007-05-03 13:45 ` Arnd Bergmann
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