From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56173) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGKMG-0003YT-Li for qemu-devel@nongnu.org; Fri, 24 Jun 2016 02:12:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bGKMA-0001qu-IF for qemu-devel@nongnu.org; Fri, 24 Jun 2016 02:12:51 -0400 Date: Fri, 24 Jun 2016 14:12:31 +0800 From: Fam Zheng Message-ID: <20160624061231.GA13266@ad.usersys.redhat.com> References: <1466721446-27737-1-git-send-email-eblake@redhat.com> <1466721446-27737-17-git-send-email-eblake@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466721446-27737-17-git-send-email-eblake@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 16/22] block: Wording tweaks to write zeroes limits List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, kwolf@redhat.com, stefanha@redhat.com, Max Reitz On Thu, 06/23 16:37, Eric Blake wrote: > Improve the documentation of the write zeroes limits, to mention > additional constraints that drivers should observe. Worth squashing > into commit cf081fca, if that hadn't been pushed already :) > > Signed-off-by: Eric Blake > > --- > v3: new patch, split off from "block: Switch discard length bounds..." > --- > include/block/block_int.h | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/include/block/block_int.h b/include/block/block_int.h > index 7d2b152..7a4a00f 100644 > --- a/include/block/block_int.h > +++ b/include/block/block_int.h > @@ -331,11 +331,14 @@ typedef struct BlockLimits { > int64_t discard_alignment; > > /* maximum number of bytes that can zeroized at once (since it is > - * signed, it must be < 2G, if set) */ > + * signed, it must be < 2G, if set), should be multiple of > + * pwrite_zeroes_alignment. May be 0 if no inherent 32-bit limit */ "inherent 32-bit limit"? What is special about 32-bit other than this field is 32-bit? Anyway, Reviewed-by: Fam Zheng > int32_t max_pwrite_zeroes; > > /* optimal alignment for write zeroes requests in bytes, must be > - * power of 2, and less than max_pwrite_zeroes if that is set */ > + * power of 2, less than max_pwrite_zeroes if that is set, and > + * multiple of bs->request_alignment. May be 0 if > + * bs->request_alignment is good enough */ > uint32_t pwrite_zeroes_alignment; > > /* optimal transfer length in bytes (must be power of 2, and > -- > 2.5.5 >