Message ID | 20180704042221.GG4809@rapoport-lnx (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Hi Mike, On 04/07/18 14:22, Mike Rapoport wrote: > On Wed, Jul 04, 2018 at 12:02:52PM +1000, Greg Ungerer wrote: >> On 04/07/18 11:39, Greg Ungerer wrote: >>> On 03/07/18 20:29, Mike Rapoport wrote: >>>> In m68k the physical memory is described by [memory_start, memory_end] for >>>> !MMU variant and by m68k_memory array of memory ranges for the MMU version. >>>> This information is directly used to register the physical memory with >>>> memblock. >>>> >>>> The reserve_bootmem() calls are replaced with memblock_reserve() and the >>>> bootmap bitmap allocation is simply dropped. >>>> >>>> Since the MMU variant creates early mappings only for the small part of the >>>> memory we force bottom-up allocations in memblock because otherwise we will >>>> attempt to access memory that not yet mapped >>>> >>>> Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> >>> >>> This builds cleanly for me with a m5475_defconfig, but it fails >>> to boot on real hardware. No console, no nothing on startup. >>> I haven't debugged any further yet. >>> >>> The M5475 is a ColdFire with MMU enabled target. >> >> With some early serial debug trace I see: >> >> Linux version 4.18.0-rc3-00003-g109f5e551b18-dirty (gerg@goober) (gcc version 5.4.0 (GCC)) #5 Wed Jul 4 12:00:03 AEST 2018 >> On node 0 totalpages: 4096 >> DMA zone: 18 pages used for memmap >> DMA zone: 0 pages reserved >> DMA zone: 4096 pages, LIFO batch:0 >> pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768 >> pcpu-alloc: [0] 0 >> Built 1 zonelists, mobility grouping off. Total pages: 4078 >> Kernel command line: root=/dev/mtdblock0 >> Dentry cache hash table entries: 4096 (order: 1, 16384 bytes) >> Inode-cache hash table entries: 2048 (order: 0, 8192 bytes) >> Sorting __ex_table... >> Memory: 3032K/32768K available (1489K kernel code, 96K rwdata, 240K rodata, 56K init, 77K bss, 29736K reserved, 0K cma-reserved) > ^^^^^^ > It seems I was over enthusiastic when I reserved the memory for the kernel. > Can you please try with the below patch: > > diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c > index e9e60e1..18c7bf6 100644 > --- a/arch/m68k/mm/mcfmmu.c > +++ b/arch/m68k/mm/mcfmmu.c > @@ -174,7 +174,7 @@ void __init cf_bootmem_alloc(void) > high_memory = (void *)_ramend; > > /* Reserve kernel text/data/bss */ > - memblock_reserve(memstart, _ramend - memstart); > + memblock_reserve(memstart, memstart - _rambase); > > m68k_virt_to_node_shift = fls(_ramend - 1) - 6; > module_fixup(NULL, __start_fixup, __stop_fixup); > diff --git a/mm/memblock.c b/mm/memblock.c > index 03d48d8..98661be 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -54,7 +54,7 @@ struct memblock memblock __initdata_memblock = { > .current_limit = MEMBLOCK_ALLOC_ANYWHERE, > }; > > -int memblock_debug __initdata_memblock; > +int memblock_debug __initdata_memblock = 1; > static bool system_has_some_mirror __initdata_memblock = false; > static int memblock_can_resize __initdata_memblock; > static int memblock_memory_in_slab __initdata_memblock = 0; > > > The memblock hunk is needed to see early memblock debug messages as all the > setup happens before parsing of the command line. Ok, that works, boots all the way up now. Linux version 4.18.0-rc3-00003-g109f5e551b18-dirty (gerg@goober) (gcc version 5.4.0 (GCC)) #7 Wed Jul 4 14:34:48 AEST 2018 memblock_add: [0x00000000-0x01ffffff] 0x001ebaa0 memblock_reserve: [0x00332000-0x00663fff] 0x001ebafa memblock_reserve: [0x01ffe000-0x01ffffff] 0x001efd38 memblock_reserve: [0x01ff8000-0x01ffdfff] 0x001efd38 memblock_virt_alloc_try_nid_nopanic: 147456 bytes align=0x0 nid=0 from=0x0 max_addr=0x0 0x00190dea memblock_reserve: [0x01fd4000-0x01ff7fff] 0x001f0466 memblock_virt_alloc_try_nid_nopanic: 4 bytes align=0x0 nid=0 from=0x0 max_addr=0x0 0x001ee234 memblock_reserve: [0x01fd3ff0-0x01fd3ff3] 0x001f0466 memblock_virt_alloc_try_nid: 20 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ea488 memblock_reserve: [0x01fd3fd0-0x01fd3fe3] 0x001f0466 memblock_virt_alloc_try_nid: 20 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ea4a8 memblock_reserve: [0x01fd3fb0-0x01fd3fc3] 0x001f0466 memblock_virt_alloc_try_nid: 20 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ea4c0 memblock_reserve: [0x01fd3f90-0x01fd3fa3] 0x001f0466 memblock_virt_alloc_try_nid_nopanic: 8192 bytes align=0x2000 nid=-1 from=0x0 max_addr=0x0 0x001eef30 memblock_reserve: [0x01fd0000-0x01fd1fff] 0x001f0466 memblock_virt_alloc_try_nid_nopanic: 32768 bytes align=0x2000 nid=-1 from=0x0 max_addr=0x0 0x001ef5d6 memblock_reserve: [0x01fc8000-0x01fcffff] 0x001f0466 memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2ac memblock_reserve: [0x01fd3f80-0x01fd3f83] 0x001f0466 memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2c2 memblock_reserve: [0x01fd3f70-0x01fd3f73] 0x001f0466 memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2d6 memblock_reserve: [0x01fd3f60-0x01fd3f63] 0x001f0466 memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2e6 memblock_reserve: [0x01fd3f50-0x01fd3f53] 0x001f0466 memblock_virt_alloc_try_nid: 120 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef506 memblock_reserve: [0x01fd3ed0-0x01fd3f47] 0x001f0466 memblock_virt_alloc_try_nid: 67 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eece0 memblock_reserve: [0x01fd3e80-0x01fd3ec2] 0x001f0466 memblock_virt_alloc_try_nid: 1024 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eed0e memblock_reserve: [0x01fd3a80-0x01fd3e7f] 0x001f0466 memblock_virt_alloc_try_nid: 1028 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eed2c memblock_reserve: [0x01fd3670-0x01fd3a73] 0x001f0466 memblock_virt_alloc_try_nid: 80 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eed4e memblock_reserve: [0x01fd3620-0x01fd366f] 0x001f0466 __memblock_free_early: [0x00000001fd0000-0x00000001fd1fff] 0x001eef80 Built 1 zonelists, mobility grouping off. Total pages: 4078 Kernel command line: root=/dev/mtdblock0 memblock_virt_alloc_try_nid_nopanic: 16384 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ee828 memblock_reserve: [0x01fc4000-0x01fc7fff] 0x001f0466 Dentry cache hash table entries: 4096 (order: 1, 16384 bytes) memblock_virt_alloc_try_nid_nopanic: 8192 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ee828 memblock_reserve: [0x01fd1620-0x01fd361f] 0x001f0466 Inode-cache hash table entries: 2048 (order: 0, 8192 bytes) Sorting __ex_table... Memory: 29256K/32768K available (1489K kernel code, 96K rwdata, 240K rodata, 56K init, 77K bss, 3512K reserved, 0K cma-reserved) SLUB: HWalign=16, Order=0-3, MinObjects=0, CPUs=1, Nodes=8 NR_IRQS: 256 clocksource: slt: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 14370379300 ns Calibrating delay loop... 264.19 BogoMIPS (lpj=1320960) pid_max: default: 32768 minimum: 301 Mount-cache hash table entries: 2048 (order: 0, 8192 bytes) Mountpoint-cache hash table entries: 2048 (order: 0, 8192 bytes) clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns ColdFire: PCI bus initialization... Coldfire: PCI IO/config window mapped to 0xe0000000 PCI host bridge to bus 0000:00 pci_bus 0000:00: root bus resource [io 0x0000-0xffff] pci_bus 0000:00: root bus resource [mem 0x00000000-0xffffffff] pci_bus 0000:00: root bus resource [bus 00-ff] pci 0000:00:14.0: BAR 2: assigned [mem 0xf0000000-0xf00fffff] pci 0000:00:14.0: BAR 6: assigned [mem 0xf0100000-0xf01fffff pref] pci 0000:00:14.0: BAR 0: assigned [mem 0xf0200000-0xf0200fff] pci 0000:00:14.0: BAR 1: assigned [io 0x0400-0x043f] vgaarb: loaded clocksource: Switched to clocksource slt workingset: timestamp_bits=27 max_order=12 bucket_order=0 romfs: ROMFS MTD (C) 2007 Red Hat, Inc. io scheduler noop registered (default) io scheduler mq-deadline registered io scheduler kyber registered ColdFire internal UART serial driver mcfuart.0: ttyS0 at MMIO 0xff008600 (irq = 99, base_baud = 8312500) is a ColdFire UART console [ttyS0] enabled mcfuart.0: ttyS1 at MMIO 0xff008700 (irq = 98, base_baud = 8312500) is a ColdFire UART mcfuart.0: ttyS2 at MMIO 0xff008800 (irq = 97, base_baud = 8312500) is a ColdFire UART mcfuart.0: ttyS3 at MMIO 0xff008900 (irq = 96, base_baud = 8312500) is a ColdFire UART brd: module loaded uclinux[mtd]: probe address=0x20bb84 size=0x126000 Creating 1 MTD partitions on "ram": 0x000000000000-0x000000126000 : "ROMfs" random: get_random_bytes called from 0x000283b6 with crng_init=0 VFS: Mounted root (romfs filesystem) readonly on device 31:0. Freeing unused kernel memory: 56K This architecture does not have kernel memory protection. Regards Greg
Hi Greg, On Wed, Jul 04, 2018 at 02:39:05PM +1000, Greg Ungerer wrote: > Hi Mike, > > On 04/07/18 14:22, Mike Rapoport wrote: > >On Wed, Jul 04, 2018 at 12:02:52PM +1000, Greg Ungerer wrote: > >>On 04/07/18 11:39, Greg Ungerer wrote: > >>>On 03/07/18 20:29, Mike Rapoport wrote: > >>>>In m68k the physical memory is described by [memory_start, memory_end] for > >>>>!MMU variant and by m68k_memory array of memory ranges for the MMU version. > >>>>This information is directly used to register the physical memory with > >>>>memblock. > >>>> > >>>>The reserve_bootmem() calls are replaced with memblock_reserve() and the > >>>>bootmap bitmap allocation is simply dropped. > >>>> > >>>>Since the MMU variant creates early mappings only for the small part of the > >>>>memory we force bottom-up allocations in memblock because otherwise we will > >>>>attempt to access memory that not yet mapped > >>>> > >>>>Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> > >>> > >>>This builds cleanly for me with a m5475_defconfig, but it fails > >>>to boot on real hardware. No console, no nothing on startup. > >>>I haven't debugged any further yet. > >>> > >>>The M5475 is a ColdFire with MMU enabled target. > >> > >>With some early serial debug trace I see: > >> > >>Linux version 4.18.0-rc3-00003-g109f5e551b18-dirty (gerg@goober) (gcc version 5.4.0 (GCC)) #5 Wed Jul 4 12:00:03 AEST 2018 > >>On node 0 totalpages: 4096 > >> DMA zone: 18 pages used for memmap > >> DMA zone: 0 pages reserved > >> DMA zone: 4096 pages, LIFO batch:0 > >>pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768 > >>pcpu-alloc: [0] 0 > >>Built 1 zonelists, mobility grouping off. Total pages: 4078 > >>Kernel command line: root=/dev/mtdblock0 > >>Dentry cache hash table entries: 4096 (order: 1, 16384 bytes) > >>Inode-cache hash table entries: 2048 (order: 0, 8192 bytes) > >>Sorting __ex_table... > >>Memory: 3032K/32768K available (1489K kernel code, 96K rwdata, 240K rodata, 56K init, 77K bss, 29736K reserved, 0K cma-reserved) > > ^^^^^^ > >It seems I was over enthusiastic when I reserved the memory for the kernel. > >Can you please try with the below patch: > > > >diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c > >index e9e60e1..18c7bf6 100644 > >--- a/arch/m68k/mm/mcfmmu.c > >+++ b/arch/m68k/mm/mcfmmu.c > >@@ -174,7 +174,7 @@ void __init cf_bootmem_alloc(void) > > high_memory = (void *)_ramend; > > /* Reserve kernel text/data/bss */ > >- memblock_reserve(memstart, _ramend - memstart); > >+ memblock_reserve(memstart, memstart - _rambase); > > m68k_virt_to_node_shift = fls(_ramend - 1) - 6; > > module_fixup(NULL, __start_fixup, __stop_fixup); > >diff --git a/mm/memblock.c b/mm/memblock.c > >index 03d48d8..98661be 100644 > >--- a/mm/memblock.c > >+++ b/mm/memblock.c > >@@ -54,7 +54,7 @@ struct memblock memblock __initdata_memblock = { > > .current_limit = MEMBLOCK_ALLOC_ANYWHERE, > > }; > >-int memblock_debug __initdata_memblock; > >+int memblock_debug __initdata_memblock = 1; > > static bool system_has_some_mirror __initdata_memblock = false; > > static int memblock_can_resize __initdata_memblock; > > static int memblock_memory_in_slab __initdata_memblock = 0; > > > > > >The memblock hunk is needed to see early memblock debug messages as all the > >setup happens before parsing of the command line. > > Ok, that works, boots all the way up now. Thanks for testing. I'll send v2 later on today. > Linux version 4.18.0-rc3-00003-g109f5e551b18-dirty (gerg@goober) (gcc version 5.4.0 (GCC)) #7 Wed Jul 4 14:34:48 AEST 2018 > memblock_add: [0x00000000-0x01ffffff] 0x001ebaa0 > memblock_reserve: [0x00332000-0x00663fff] 0x001ebafa > memblock_reserve: [0x01ffe000-0x01ffffff] 0x001efd38 > memblock_reserve: [0x01ff8000-0x01ffdfff] 0x001efd38 > memblock_virt_alloc_try_nid_nopanic: 147456 bytes align=0x0 nid=0 from=0x0 max_addr=0x0 0x00190dea > memblock_reserve: [0x01fd4000-0x01ff7fff] 0x001f0466 > memblock_virt_alloc_try_nid_nopanic: 4 bytes align=0x0 nid=0 from=0x0 max_addr=0x0 0x001ee234 > memblock_reserve: [0x01fd3ff0-0x01fd3ff3] 0x001f0466 > memblock_virt_alloc_try_nid: 20 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ea488 > memblock_reserve: [0x01fd3fd0-0x01fd3fe3] 0x001f0466 > memblock_virt_alloc_try_nid: 20 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ea4a8 > memblock_reserve: [0x01fd3fb0-0x01fd3fc3] 0x001f0466 > memblock_virt_alloc_try_nid: 20 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ea4c0 > memblock_reserve: [0x01fd3f90-0x01fd3fa3] 0x001f0466 > memblock_virt_alloc_try_nid_nopanic: 8192 bytes align=0x2000 nid=-1 from=0x0 max_addr=0x0 0x001eef30 > memblock_reserve: [0x01fd0000-0x01fd1fff] 0x001f0466 > memblock_virt_alloc_try_nid_nopanic: 32768 bytes align=0x2000 nid=-1 from=0x0 max_addr=0x0 0x001ef5d6 > memblock_reserve: [0x01fc8000-0x01fcffff] 0x001f0466 > memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2ac > memblock_reserve: [0x01fd3f80-0x01fd3f83] 0x001f0466 > memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2c2 > memblock_reserve: [0x01fd3f70-0x01fd3f73] 0x001f0466 > memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2d6 > memblock_reserve: [0x01fd3f60-0x01fd3f63] 0x001f0466 > memblock_virt_alloc_try_nid: 4 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef2e6 > memblock_reserve: [0x01fd3f50-0x01fd3f53] 0x001f0466 > memblock_virt_alloc_try_nid: 120 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ef506 > memblock_reserve: [0x01fd3ed0-0x01fd3f47] 0x001f0466 > memblock_virt_alloc_try_nid: 67 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eece0 > memblock_reserve: [0x01fd3e80-0x01fd3ec2] 0x001f0466 > memblock_virt_alloc_try_nid: 1024 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eed0e > memblock_reserve: [0x01fd3a80-0x01fd3e7f] 0x001f0466 > memblock_virt_alloc_try_nid: 1028 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eed2c > memblock_reserve: [0x01fd3670-0x01fd3a73] 0x001f0466 > memblock_virt_alloc_try_nid: 80 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001eed4e > memblock_reserve: [0x01fd3620-0x01fd366f] 0x001f0466 > __memblock_free_early: [0x00000001fd0000-0x00000001fd1fff] 0x001eef80 > Built 1 zonelists, mobility grouping off. Total pages: 4078 > Kernel command line: root=/dev/mtdblock0 > memblock_virt_alloc_try_nid_nopanic: 16384 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ee828 > memblock_reserve: [0x01fc4000-0x01fc7fff] 0x001f0466 > Dentry cache hash table entries: 4096 (order: 1, 16384 bytes) > memblock_virt_alloc_try_nid_nopanic: 8192 bytes align=0x0 nid=-1 from=0x0 max_addr=0x0 0x001ee828 > memblock_reserve: [0x01fd1620-0x01fd361f] 0x001f0466 > Inode-cache hash table entries: 2048 (order: 0, 8192 bytes) > Sorting __ex_table... > Memory: 29256K/32768K available (1489K kernel code, 96K rwdata, 240K rodata, 56K init, 77K bss, 3512K reserved, 0K cma-reserved) > SLUB: HWalign=16, Order=0-3, MinObjects=0, CPUs=1, Nodes=8 > NR_IRQS: 256 > clocksource: slt: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 14370379300 ns > Calibrating delay loop... 264.19 BogoMIPS (lpj=1320960) > pid_max: default: 32768 minimum: 301 > Mount-cache hash table entries: 2048 (order: 0, 8192 bytes) > Mountpoint-cache hash table entries: 2048 (order: 0, 8192 bytes) > clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns > ColdFire: PCI bus initialization... > Coldfire: PCI IO/config window mapped to 0xe0000000 > PCI host bridge to bus 0000:00 > pci_bus 0000:00: root bus resource [io 0x0000-0xffff] > pci_bus 0000:00: root bus resource [mem 0x00000000-0xffffffff] > pci_bus 0000:00: root bus resource [bus 00-ff] > pci 0000:00:14.0: BAR 2: assigned [mem 0xf0000000-0xf00fffff] > pci 0000:00:14.0: BAR 6: assigned [mem 0xf0100000-0xf01fffff pref] > pci 0000:00:14.0: BAR 0: assigned [mem 0xf0200000-0xf0200fff] > pci 0000:00:14.0: BAR 1: assigned [io 0x0400-0x043f] > vgaarb: loaded > clocksource: Switched to clocksource slt > workingset: timestamp_bits=27 max_order=12 bucket_order=0 > romfs: ROMFS MTD (C) 2007 Red Hat, Inc. > io scheduler noop registered (default) > io scheduler mq-deadline registered > io scheduler kyber registered > ColdFire internal UART serial driver > mcfuart.0: ttyS0 at MMIO 0xff008600 (irq = 99, base_baud = 8312500) is a ColdFire UART > console [ttyS0] enabled > mcfuart.0: ttyS1 at MMIO 0xff008700 (irq = 98, base_baud = 8312500) is a ColdFire UART > mcfuart.0: ttyS2 at MMIO 0xff008800 (irq = 97, base_baud = 8312500) is a ColdFire UART > mcfuart.0: ttyS3 at MMIO 0xff008900 (irq = 96, base_baud = 8312500) is a ColdFire UART > brd: module loaded > uclinux[mtd]: probe address=0x20bb84 size=0x126000 > Creating 1 MTD partitions on "ram": > 0x000000000000-0x000000126000 : "ROMfs" > random: get_random_bytes called from 0x000283b6 with crng_init=0 > VFS: Mounted root (romfs filesystem) readonly on device 31:0. > Freeing unused kernel memory: 56K > This architecture does not have kernel memory protection. > > Regards > Greg >
diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c index e9e60e1..18c7bf6 100644 --- a/arch/m68k/mm/mcfmmu.c +++ b/arch/m68k/mm/mcfmmu.c @@ -174,7 +174,7 @@ void __init cf_bootmem_alloc(void) high_memory = (void *)_ramend; /* Reserve kernel text/data/bss */ - memblock_reserve(memstart, _ramend - memstart); + memblock_reserve(memstart, memstart - _rambase); m68k_virt_to_node_shift = fls(_ramend - 1) - 6; module_fixup(NULL, __start_fixup, __stop_fixup); diff --git a/mm/memblock.c b/mm/memblock.c index 03d48d8..98661be 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -54,7 +54,7 @@ struct memblock memblock __initdata_memblock = { .current_limit = MEMBLOCK_ALLOC_ANYWHERE, }; -int memblock_debug __initdata_memblock; +int memblock_debug __initdata_memblock = 1; static bool system_has_some_mirror __initdata_memblock = false; static int memblock_can_resize __initdata_memblock; static int memblock_memory_in_slab __initdata_memblock = 0;