On Wed, Jan 11, 2023 at 09:05:05AM +0100, Stefan Roese wrote:
> On 1/11/23 02:32, AKASHI Takahiro wrote:
> > Hi,
> >
> > Thank you for catching this issue.
> >
> > On Tue, Jan 10, 2023 at 09:00:38AM +0100, Stefan Roese wrote:
> > > I've noticed that the first ext4 file loading from a MMC partition for
> > > ZynqMP takes quite some time (~ 1 second). Debugging showed, that the
> > > MMC driver reads the partition info 128 time (MAX_SEARCH_PARTITIONS)
> > > resulting in this boot delay. To fix this, let's just end creating the
> > > block drives in part_create_block_devices() when no more valid partition
> > > is found. This reduces the first file reading from ~0.9s to ~0.3s.
> > >
> > > Signed-off-by: Stefan Roese <s...@denx.de>
> > > Cc: Simon Glass <s...@chromium.org>
> > > Cc: AKASHI Takahiro <takahiro.aka...@linaro.org>
> > > Cc: Heinrich Schuchardt <xypron.g...@gmx.de>
> > > ---
> > > Reasoning for RFC:
> > > I did not dig into the current disk / partition stuff too deeply, so I'm
> > > not 100% sure that this patch does not break anything.
> >
> > I'm afraid that this fix won't work for all the partition types,
> > especially for those in which entries in a partition table can be sparsely
> > filled,
> > or in other words, valid partition numbers may not always be contiguous
> > even if they don't reach a maximum number.
>
> So what is the maximum number? Where originates the
> MAX_SEARCH_PARTITIONS = 128 from?
commit bc314f8e5f9b ("cmd: part: list all 128 GPT partitions")
But GPT may accept arbitrary number of partitions.
The GPT header has "num_partition_entries" for the table size.
The max depends on partition types.
> > I somehow confirmed this against a GPT partition by using gdisk.
>
> How exactly did you confirm this?
Created partitions for, say, #3 and #5 by 'n' command.
-Takahiro Akashi
> Thanks,
> Stefan
>
> > -Takahiro Akashi
> >
> > > ---
> > > disk/disk-uclass.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/disk/disk-uclass.c b/disk/disk-uclass.c
> > > index d32747e2242d..2999f7285b5a 100644
> > > --- a/disk/disk-uclass.c
> > > +++ b/disk/disk-uclass.c
> > > @@ -36,7 +36,7 @@ int part_create_block_devices(struct udevice *blk_dev)
> > > /* Add devices for each partition */
> > > for (count = 0, part = 1; part <= MAX_SEARCH_PARTITIONS;
> > > part++) {
> > > if (part_get_info(desc, part, &info))
> > > - continue;
> > > + break;
> > > snprintf(devname, sizeof(devname), "%s:%d",
> > > blk_dev->name,
> > > part);
> > > --
> > > 2.39.0
> > >
>
> Viele Grüße,
> Stefan Roese
>
> --
> DENX Software Engineering GmbH, Managing Director: Erika Unter
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: s...@denx.de
