> -----Original Message-----
> From: Klaus Jensen <i...@irrelevant.dk>
> Sent: Tuesday, September 15, 2020 3:34 AM
> To: Dmitry Fomichev <dmitry.fomic...@wdc.com>
> Cc: Keith Busch <kbu...@kernel.org>; Klaus Jensen
> <k.jen...@samsung.com>; Kevin Wolf <kw...@redhat.com>; Philippe
> Mathieu-Daudé <phi...@redhat.com>; Maxim Levitsky
> <mlevi...@redhat.com>; Fam Zheng <f...@euphon.net>; Niklas Cassel
> <niklas.cas...@wdc.com>; Damien Le Moal <damien.lem...@wdc.com>;
> qemu-block@nongnu.org; qemu-de...@nongnu.org; Alistair Francis
> <alistair.fran...@wdc.com>; Matias Bjorling <matias.bjorl...@wdc.com>
> Subject: Re: [PATCH v3 02/15] hw/block/nvme: Report actual LBA data shift in
> LBAF
>
> On Sep 14 07:14, Dmitry Fomichev wrote:
> > Calculate the data shift value to report based on the set value of
> > logical_block_size device property.
> >
> > In the process, use a local variable to calculate the LBA format
> > index instead of the hardcoded value 0. This makes the code more
> > readable and it will make it easier to add support for multiple LBA
> > formats in the future.
> >
> > Signed-off-by: Dmitry Fomichev <dmitry.fomic...@wdc.com>
> > ---
> > hw/block/nvme.c | 4 +++-
> > hw/block/nvme.h | 11 +++++++++++
> > 2 files changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> > index 3a90d80694..1cfc136042 100644
> > --- a/hw/block/nvme.c
> > +++ b/hw/block/nvme.c
> > @@ -2203,6 +2203,7 @@ static void nvme_init_namespace(NvmeCtrl *n,
> NvmeNamespace *ns, Error **errp)
> > {
> > int64_t bs_size;
> > NvmeIdNs *id_ns = &ns->id_ns;
> > + int lba_index;
> >
> > bs_size = blk_getlength(n->conf.blk);
> > if (bs_size < 0) {
> > @@ -2212,7 +2213,8 @@ static void nvme_init_namespace(NvmeCtrl *n,
> NvmeNamespace *ns, Error **errp)
> >
> > n->ns_size = bs_size;
> >
> > - id_ns->lbaf[0].ds = BDRV_SECTOR_BITS;
> > + lba_index = NVME_ID_NS_FLBAS_INDEX(ns->id_ns.flbas);
> > + id_ns->lbaf[lba_index].ds = nvme_ilog2(n->conf.logical_block_size);
>
> Instead of defining a new function, we can directly use clz32().
>
> 31 - clz32(n->conf.logical_block_size)
Ok nice! I looked up what QEMU uses for binary log, but couldn't find it quickly
so I decided to define a function for that :) Will switch to clzXX in the patch
set -
I believe there are three occurrences where ilog2 is used in the added code.
