RE: problem with exfat on 4k logical sector devices

["Namjae Jeon" <namjae.jeon@samsung.com>]

> On 5/11/21 4:21 PM, Namjae Jeon wrote:
> >> Hi Namjae -
> > Hi Eric,
> >>
> >> It seems that exfat is unhappy on 4k logical sector size devices:
> > Thanks for your report!
> > We have got same report from Christophe Vu-Brugier. And he sent us the
> > patch(https://protect2.fireeye.com/v1/url?k=ac8f77ef-f3144ef5-ac8efca0
> > -000babff24ad-8b7be88b031de920&q=1&e=0e9634f8-7ff9-4eb8-b5af-2316b62e9
> > 236&u=https%3A%2F%2Fgithub.com%2Fexfatprogs%2Fexfatprogs%2Fpull%2F164)
> > to fix it yesterday.(Thanks Christophe!), I will check it today
> 
> Oh, good timing! ;)
> 
> gI'll try to look at that in more depth. It does seem to make everything work for me, and resolves a
> couple other misunderstandings I may have had, and they seem to match with the spec.
> 
> For example, I now see that boot sector signature does go at the end of 512 for the primary boot
> sector, and at the end of $SECTOR_SIZE for the extended boot sector.
Thanks for your check:)

> 
> One other thing that I ran across is that fsck seems to validate an image against the sector size of
> the device hosting the image rather than the sector size found in the boot sector, which seems like
> another issue that will come up:
> 
> # fsck/fsck.exfat /dev/sdb
> exfatprogs version : 1.1.1
> /dev/sdb: clean. directories 1, files 0
> 
> # dd if=/dev/sdb of=test.img
> 524288+0 records in
> 524288+0 records out
> 268435456 bytes (268 MB) copied, 1.27619 s, 210 MB/s
> 
> # fsck.exfat test.img
> exfatprogs version : 1.1.1
> checksum of boot region is not correct. 0, but expected 0x3ee721 boot region is corrupted. try to
> restore the region from backup. Fix (y/N)? n
> 
> Right now the utilities seem to assume that the device they're pointed at is always a block device,
> and image files are problematic.
Okay, Will fix it.
> 
> Also, as an aside, it might be useful to have a "set sector size" commandline option at least for
> testing, or to create 4k images that could be transferred to a 4k device.
Agreed, We will add that option:)

Thanks!
> 
> Thanks,
> -Eric