From: Olof Johansson <olof@lixom•net>
To: Manish Ahuja <ahuja@austin•ibm.com>
Cc: mahuja@us•ibm.com, linuxppc-dev@ozlabs•org,
linasvepstas@gmail•com, paulus@samba•org
Subject: Re: [PATCH] pseries: phyp dump: Variable size reserve space.
Date: Wed, 9 Apr 2008 13:30:32 -0500 [thread overview]
Message-ID: <20080409183032.GA2360@lixom.net> (raw)
In-Reply-To: <47FCFEEF.6020607@austin.ibm.com>
On Wed, Apr 09, 2008 at 12:37:51PM -0500, Manish Ahuja wrote:
> Olof Johansson wrote:
> >> +static inline unsigned long phyp_dump_calculate_reserve_size(void)
> >> +{
> >> + unsigned long tmp;
> >> +
> >> + if (phyp_dump_info->phyp_dump_reserve_bootvar)
> >> + return phyp_dump_info->phyp_dump_reserve_bootvar;
> >> +
> >> + /* divide by 20 to get 5% of value */
> >> + tmp = lmb_end_of_DRAM();
> >> + do_div(tmp, 20);
> >> +
> >> + /* round it down in multiples of 256 */
> >> + tmp = tmp & ~0x000000001FFFFFFF;
> >
> > That's 512MB, isn't it?
>
> My calculations in the example I gave in the last email were wrong.
>
> In mentally did 10% instead of 5%. But the premise is same.
>
> So assuming 5% of some memory is 400 MB, it rounds it down to 256MB etc.
But 0x1fffffff is 512MB, not 256MB. So you're rounding it down to a
multiple of 512MB.
-Olof
next prev parent reply other threads:[~2008-04-09 18:19 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-07 23:45 [PATCH] pseries: phyp dump: Variable size reserve space Manish Ahuja
2008-04-08 2:43 ` Olof Johansson
2008-04-09 17:32 ` Manish Ahuja
2008-04-09 19:39 ` Segher Boessenkool
2008-04-10 1:36 ` Paul Mackerras
2008-04-10 3:10 ` Segher Boessenkool
2008-04-09 17:37 ` Manish Ahuja
2008-04-09 18:30 ` Olof Johansson [this message]
2008-04-09 18:43 ` Manish Ahuja
2008-04-09 18:59 ` Olof Johansson
2008-04-11 23:31 ` Manish Ahuja
2008-04-15 6:24 ` Paul Mackerras
2008-04-15 22:56 ` Manish Ahuja
2008-04-16 19:42 ` Joel Schopp
2008-04-16 20:22 ` Linas Vepstas
2008-04-18 19:08 ` Manish Ahuja
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