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SubjectRe: [PATCH V7 1/3] genalloc:support memory-allocation with bytes-alignment to genalloc
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On Sat, 2015-09-05 at 22:13 -0500, Zhao Qiang-B45475 wrote:
> On Wed, 2015-09-02 at 10:18AM +0800, Wood Scott-B07421 wrote:
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Wednesday, September 02, 2015 10:18 AM
> > To: Zhao Qiang-B45475
> > Cc: linux-kernel@vger.kernel.org; linuxppc-dev@lists.ozlabs.org;
> > lauraa@codeaurora.org; Xie Xiaobo-R63061; benh@kernel.crashing.org; Li
> > Yang-Leo-R58472; paulus@samba.org
> > Subject: Re: [PATCH V7 1/3] genalloc:support memory-allocation with
> > bytes-alignment to genalloc
> >
> > On Tue, 2015-09-01 at 21:10 -0500, Zhao Qiang-B45475 wrote:
> > > On Wed, 2015-09-02 at 08:38AM +0800, Wood Scott-B07421 wrote:
> > > > -----Original Message-----
> > > > From: Wood Scott-B07421
> > > > Sent: Wednesday, September 02, 2015 8:30 AM
> > > > To: Zhao Qiang-B45475
> > > > Cc: linux-kernel@vger.kernel.org; linuxppc-dev@lists.ozlabs.org;
> > > > lauraa@codeaurora.org; Xie Xiaobo-R63061; benh@kernel.crashing.org;
> > > > Li Yang-Leo-R58472; paulus@samba.org
> > > > Subject: Re: [PATCH V7 1/3] genalloc:support memory-allocation with
> > > > bytes-alignment to genalloc
> > > >
> > > > On Mon, 2015-08-31 at 16:58 +0800, Zhao Qiang wrote:
> > > > > Bytes alignment is required to manage some special RAM, so add
> > > > > gen_pool_first_fit_align to genalloc, meanwhile add
> > > > > gen_pool_alloc_data to pass data to
> > > > > gen_pool_first_fit_align(modify gen_pool_alloc as a wrapper)
> > > > >
> > > > > Signed-off-by: Zhao Qiang <qiang.zhao@freescale.com>
> > > > > ---
> > > > > Changes for v6:
> > > > > - patches set v6 include a new patch because of using
> > > > > - genalloc to manage QE MURAM, patch 0001 is the new
> > > > > - patch, adding bytes alignment for allocation for use.
> > > > > Changes for v7:
> > > > > - cpm muram also need to use genalloc to manage, it has
> > > > > a function to reserve a specific region of muram,
> > > > > add offset to genpool_data for start addr to be allocated.
> > > >
> > > > This seems to be describing more than just the changes in this patch.
> > > > What does also handling cpm have to do with this patch? Are you
> > > > adding support for reserving a specific region in this patch? I
> > > > don't see it, and in any case it should go in a different patch.
> > >
> > > Yes, I added. The code below can support the function.
> > > offset_bit = (alignment->offset + (1UL << order) - 1) >> order;
> > > return bitmap_find_next_zero_area(map, size, start + offset_bit,
> > nr,
> > > align_mask);
> > >
> > > CPM has an function cpm_muram_alloc_fixed, needing to allocate muram
> > > from a Specific offset. So I add the code and add offset to struct data.
> >
> > I thought the offset was related to the previous discussion of checking
> > for allocation failure. Are you using it to implement alloc_fixed()? If
> > so, please don't. Besides the awkward implementation (what does it
> > logically have to do with gen_pool_first_fit_align?), it does not appear
> > to be correct -
> > - what happens with multiple chunks? What happens if part of the region
> > the caller is trying to reserve is already taken? Implement a proper
> > function to reserve a fixed genalloc region.
> >
> The offset is which allocation block address need to be larger than,
> Not equal to, it really like the parameter start of the algo(the bitnumber
> To start searching at).

cpm_muram_alloc_fixed() is not "search starting at this offset". It is
"reserve this exact range or fail".

-Scott



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