Date: Wed, 2 Mar 2022 10:07:47 +0100 (CET) From: Wojciech Puchar <wojtek@puchar.net> To: Eugene Grosbein <eugen@grosbein.net> Cc: freebsd-hackers@freebsd.org Subject: Re: problem with USB-CD drive Message-ID: <50bcd532-934a-31f0-855e-d643417dd89@puchar.net> In-Reply-To: <21050393-470a-8539-1324-3482d64c4870@grosbein.net> References: <197d435-6c4b-a60-4e6f-ea4ee515b8f4@puchar.net> <21050393-470a-8539-1324-3482d64c4870@grosbein.net>
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> It looks like the device or driver do not like size of reading request,
> f.e. short read. It should be possible to verify that using several ways:
>
> 1) run "ktrace -i mount_cd9660 ..." then study ouput of kdump;
847 mount_cd9660 STRU struct stat {dev=156, ino=261120, mode=040755,
nlink=2, uid=0, gid=0, rdev=2085752, atime=1581328619, mtime=15
81328630.081523000, ctime=1581328648.345917000, birthtime=315532800,
size=1024, blksize=32768, blocks=8, flags=0x0 }
847 mount_cd9660 RET lstat 0
847 mount_cd9660 CALL stat(0x7fffffffe440,0x7fffffffe3a0)
847 mount_cd9660 NAMI "/mnt"
847 mount_cd9660 STRU struct stat {dev=156, ino=261120, mode=040755,
nlink=2, uid=0, gid=0, rdev=2085752, atime=1581328619, mtime=15
81328630.081523000, ctime=1581328648.345917000, birthtime=315532800,
size=1024, blksize=32768, blocks=8, flags=0x0 }
847 mount_cd9660 RET stat 0
847 mount_cd9660 CALL openat(AT_FDCWD,0x7fffffffee6d,0<O_RDONLY>)
847 mount_cd9660 NAMI "/dev/cd1"
847 mount_cd9660 RET openat 3
847 mount_cd9660 CALL ioctl(0x3,CDIOREADTOCHEADER,0x7fffffffeb88)
847 mount_cd9660 RET ioctl 0
847 mount_cd9660 CALL ioctl(0x3,CDIOREADTOCENTRYS,0x7fffffffeb60)
847 mount_cd9660 RET ioctl 0
847 mount_cd9660 CALL close(0x3)
847 mount_cd9660 RET close 0
847 mount_cd9660 CALL
mmap(0,0x200000,0x3<PROT_READ|PROT_WRITE>,0x1002<MAP_PRIVATE|MAP_ANON>,0xffffffff,0)
847 mount_cd9660 RET mmap 34376515584/0x801000000
847 mount_cd9660 CALL nmount(0x801015080,0x8,0x1<MNT_RDONLY>)
847 mount_cd9660 NAMI "/mnt"
847 mount_cd9660 NAMI "/mnt"
847 mount_cd9660 NAMI "/dev/cd1"
847 mount_cd9660 RET nmount -1 errno 22 Invalid argument
could you please help me to understand this?
is it something about CDIOREADTOCHEADER and CDIOREADTOCENTRYS returning
not what it should return?
> 2) enable debug logs at GEOM level, use sysctl kern.geom.debugflags=255
> (beware of large amount of logs) then run mount_cd9660
> 3) use gcache(8) that is capable of limiting minimum request size by caching "extra" data,
> but try using only single gcache(8) instance per system because of known instability in the gcache code
> when you create multiple geom_cache's.
>
>
did gcache with 2kB blocks. works fine. Seems like a problem is here -
some requests are not handled.
now i tested reading it with dd with 2,4,8,16 and 32kB blocks. seems fine.
trying to read with blocks like 1k, 512 doesn't work but it is i think
normal - CDs have 2kB blocks.
real CD drive behaves the same way.
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