July 2018 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Unable to view patches in https://patchwork.kernel.org/project/LKML/list/
by nishad kamdar July 23, 2018

July 23, 2018

Hello all, I created a patch and submitted it to the following e-mail addresses. Lidza Louina <lidza.louina(a)gmail.com>,Mark Hounschell <markh(a)compro.net>,Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>,driverdev- devel@linuxdriverproject.org,devel@driverdev.osuosl.org, linux-kernel(a)vger.kernel.org. After submitting, I tried to view the patch on patchwork.kernel.org, but the webpage does not exist anymore. I could view my patches earlier on this webpage. Where can I see the patches that I submitted? Thanks, nishad kamdar

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undefined reference to `__divdi3'
by Himanshu Jha July 23, 2018

July 23, 2018

Hi, I am currently working on my GSoC project and while testing through 0-day test service, I hit the following error: drivers/iio/chemical/bme680_core.o: In function `bme680_compensate_gas': drivers/iio/chemical/bme680_core.c:450: undefined reference to `__divdi3' vim +450 drivers/iio/chemical/bme680_core.c 417 418 /* 419 * Taken from Bosch BME680 API: 420 * https://github.com/BoschSensortec/BME680_driver/blob/63bb5336/bme680.c#L973 421 * 422 * Returns gas measurement in Ohm. Output value of "82986" represent 82986 ohms. 423 */ 424 static u32 bme680_compensate_gas(struct bme680_data *data, u16 gas_res_adc, 425 u8 gas_range) 426 { 427 struct bme680_calib *calib = &data->bme680; 428 s64 var1; 429 u64 var2; 430 s64 var3; 431 u32 calc_gas_res; 432 433 /* Look up table 1 for the possible gas range values */ 434 u32 lookupTable1[16] = {2147483647u, 2147483647u, 2147483647u, 435 2147483647u, 2147483647u, 2126008810u, 436 2147483647u, 2130303777u, 2147483647u, 437 2147483647u, 2143188679u, 2136746228u, 438 2147483647u, 2126008810u, 2147483647u, 439 2147483647u}; 440 /* Look up table 2 for the possible gas range values */ 441 u32 lookupTable2[16] = {4096000000u, 2048000000u, 1024000000u, 442 512000000u, 255744255u, 127110228u, 64000000u, 443 32258064u, 16016016u, 8000000u, 4000000u, 444 2000000u, 1000000u, 500000u, 250000u, 125000u}; 445 446 var1 = ((1340 + (5 * (s64) calib->range_sw_err)) * 447 ((s64) lookupTable1[gas_range])) >> 16; 448 var2 = (((s64) ((s64) gas_res_adc << 15) - 16777216) + var1); 449 var3 = (((s64) lookupTable2[gas_range] * (s64) var1) >> 9); > 450 calc_gas_res = (u32) ((var3 + ((s64) var2 >> 1)) / (s64) var2); 451 452 return calc_gas_res; 453 } Now, I understood the problem of 64bit divison and how gcc places '__divdi3()' https://gcc.gnu.org/onlinedocs/gccint/Integer-library-routines.html to support the "freestanding" environment and support architectures which don't have such datatypes. And I need to use div64_s64() or hack around do_div() to solve the issue. Just out of curiosity, I decided to disassemble this particular function to see __divdi3 and couldn't find it! (gdb) disassemble bme680_compensate_gas Dump of assembler code for function bme680_compensate_gas: 0x0000000000000000 <+0>: call 0x5 <bme680_compensate_gas+5> 0x0000000000000005 <+5>: sub rsp,0x88 0x000000000000000c <+12>: movabs rcx,0x7eb851ea7fffffff 0x0000000000000016 <+22>: movzx edx,dl 0x0000000000000019 <+25>: mov rax,QWORD PTR gs:0x28 0x0000000000000022 <+34>: mov QWORD PTR [rsp+0x80],rax 0x000000000000002a <+42>: xor eax,eax 0x000000000000002c <+44>: movabs rax,0x7fffffff7fffffff 0x0000000000000036 <+54>: movabs r8,0x7ef9db217fffffff 0x0000000000000040 <+64>: movabs r9,0x7f5c28f47fbe76c7 0x000000000000004a <+74>: mov QWORD PTR [rsp],rax 0x000000000000004e <+78>: mov QWORD PTR [rsp+0x8],rax 0x0000000000000053 <+83>: movzx esi,si 0x0000000000000056 <+86>: mov QWORD PTR [rsp+0x20],rax 0x000000000000005b <+91>: mov QWORD PTR [rsp+0x38],rax 0x0000000000000060 <+96>: movabs rax,0x7a120000f4240000 0x000000000000006a <+106>: mov QWORD PTR [rsp+0x40],rax 0x000000000000006f <+111>: movabs rax,0x1e8480003d090000 0x0000000000000079 <+121>: mov QWORD PTR [rsp+0x10],rcx 0x000000000000007e <+126>: mov QWORD PTR [rsp+0x48],rax 0x0000000000000083 <+131>: movabs rax,0x7938c540f3e58ff 0x000000000000008d <+141>: mov QWORD PTR [rsp+0x18],r8 0x0000000000000092 <+146>: mov QWORD PTR [rsp+0x50],rax 0x0000000000000097 <+151>: movabs rax,0x1ec381003d09000 0x00000000000000a1 <+161>: mov QWORD PTR [rsp+0x28],r9 0x00000000000000a6 <+166>: mov QWORD PTR [rsp+0x58],rax 0x00000000000000ab <+171>: movabs rax,0x7a120000f46290 0x00000000000000b5 <+181>: mov QWORD PTR [rsp+0x30],rcx 0x00000000000000ba <+186>: mov QWORD PTR [rsp+0x60],rax 0x00000000000000bf <+191>: movabs rax,0x1e8480003d0900 0x00000000000000c9 <+201>: mov ecx,DWORD PTR [rsp+rdx*4] 0x00000000000000cc <+204>: mov QWORD PTR [rsp+0x68],rax 0x00000000000000d1 <+209>: movabs rax,0x7a120000f4240 0x00000000000000db <+219>: shl rsi,0xf 0x00000000000000df <+223>: mov QWORD PTR [rsp+0x70],rax 0x00000000000000e4 <+228>: movabs rax,0x1e8480003d090 0x00000000000000ee <+238>: mov QWORD PTR [rsp+0x78],rax 0x00000000000000f3 <+243>: movsx rax,BYTE PTR [rdi+0x2f] 0x00000000000000f8 <+248>: lea rax,[rax+rax*4+0x53c] 0x0000000000000100 <+256>: imul rax,rcx 0x0000000000000104 <+260>: sar rax,0x10 0x0000000000000108 <+264>: lea rsi,[rax+rsi*1-0x1000000] 0x0000000000000110 <+272>: mov rcx,rax 0x0000000000000113 <+275>: mov eax,DWORD PTR [rsp+rdx*4+0x40] 0x0000000000000117 <+279>: mov rdx,rsi 0x000000000000011a <+282>: sar rdx,1 0x000000000000011d <+285>: imul rax,rcx 0x0000000000000121 <+289>: sar rax,0x9 0x0000000000000125 <+293>: add rax,rdx 0x0000000000000128 <+296>: cqo 0x000000000000012a <+298>: idiv rsi 0x000000000000012d <+301>: mov rdi,QWORD PTR [rsp+0x80] 0x0000000000000135 <+309>: xor rdi,QWORD PTR gs:0x28 0x000000000000013e <+318>: jne 0x148 <bme680_compensate_gas+328> 0x0000000000000140 <+320>: add rsp,0x88 0x0000000000000147 <+327>: ret 0x0000000000000148 <+328>: call 0x14d End of assembler dump. So, we have here: 0x000000000000012a <+298>: idiv rsi Now, my question is, will __divdi3() be generated when I compile using -m32 gcc flag or make ARCH=i386 ? My machine is x86_64 and therefore idiv instruction is used instead of referencing __divdi3(). Isn't it ? Thanks. -- Himanshu Jha Undergraduate Student Department of Electronics & Communication Guru Tegh Bahadur Institute of Technology

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Re: undefined reference to `__divdi3'
by Himanshu Jha July 22, 2018

July 22, 2018

Hi Alan, On Sun, Jul 22, 2018 at 09:01:59PM +0200, Alan Keane wrote: > Hi Himanshu, > > >> > Hi, > > > I am currently working on my GSoC project and while testing through > 0-day test service, I hit the following error: > > drivers/iio/chemical/bme680_core.o: In function `bme680_compensate_gas': > drivers/iio/chemical/bme680_core.c:450: undefined reference to `__divdi3' > > << > > Are these errors that stop compilation or the compiler "just" giving > warnings? https://lists.01.org/pipermail/kbuild-all/2018-July/050481.html > I'm guessing they are warnings because you have an object file that you can > disassemble to find the idiv instruction? Not sure to understand the question!? > Are you building this code within the linux build system, I ask because I > work a lot on bare metal systems and see a lot of these kind of warnings, > on bare metal systems sometimes you have to implement __divdi3 (and > friends) yourself, if your code does build (with warnings) does it link and > most importantly does it (at least appear to) work? Yes, I'm building within my linux machine. The thing is when you do 64bit arithmetic operations in the code for an architecture where there is no support for such operations(i386) For instance in my code: 64 bit division calc_gas_res = (u32) ((var3 + ((s64) var2 >> 1)) / (s64) var2); In such situations, gcc provides its own runtime library(libgcc.a or libgcc_s.so.1) to perform those operations: Runtime Function: long __divdi3 (long a, long b) But the linker in the kernel compilation doesn't link libgcc and therefore, we get this error. To solve the problem we can do: 1. Use do_div() (look math64.h for more functions) to prevent build error on 32bit environments. 2. Link statically libgcc using flags: -static-libgcc -lgcc I have not cross-compiled for i386 and checked, but looking at kbuild report it likely that build terminates and no linking takes place. So, I need to use option 1. and test. I'm sure div64_s64() would solve my problem. Also, please avoid top-posting :) -- Himanshu Jha Undergraduate Student Department of Electronics & Communication Guru Tegh Bahadur Institute of Technology

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Need help in nvme queue
by Er Krishna July 20, 2018

July 20, 2018

Hi All, Does Linux kernel provide any kernel API to find the number of queues supported by Name Device which can be of vendor specific like Toshiba or Seagate or anything. Or if I can get it by reading PCIe Configuration spcae or capabilities. Please let me know how to get it from my driver code. Br/Krish

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memcpy seg fault with mmaped address
by David Frank July 20, 2018

July 20, 2018

Hi, I'm memcpy data into mmaped address with 2GB file, after a few files, it would fault with the following stack dump: received signal SIGSEGV, Segmentation fault.[Switching to Thread 0x7ffff5e95700 (LWP 3028)] __memmove_avx_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:494 494 ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S: No such file or directory. (gdb) bt #0 __memmove_avx_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:494 Any idea? Thanks, David

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Re: Linux kernel mailing list filtering issues
by Alexander Kapshuk July 20, 2018

July 20, 2018

On Fri, Jul 20, 2018 at 3:43 PM <hal(a)halemmerich.com> wrote: > > On 2018-07-19 23:55, Alexander Kapshuk wrote: > > On Thu, Jul 19, 2018 at 10:25 PM <hal(a)halemmerich.com> wrote: > >> > >> Hi all, I've been trying to post a bug report to the linux-usb mailing > >> list but keep getting trapped in the filters despite ensuring I'm > >> using > >> plaintext. > >> Heres what I get in the bounce back: > >> > >> The mail system > >> > >> <linux-usb(a)vger.kernel.org>: host vger.kernel.org[209.132.180.67] > >> said: > >> 550 > >> 5.7.1 Content-Policy accept-into-freezer-1 msg: Bayes Statistical > >> Bogofilter considers this message SPAM. BF:<S 1> In case you > >> disagree, > >> send the ENTIRE message plus this error message to > >> <postmaster(a)vger.kernel.org> ; > >> > >> I've sent the message to the postmaster but haven't heard anything. My > >> message got through to the maintainer, who has requested I fix my > >> message and get it on the mailing list proper but nothing I've tried > >> is > >> working. > >> > >> Heres part of the header from the source of my most recent message: > >> > >> MIME-Version: 1.0 > >> Content-Type: text/plain; charset=UTF-8; > >> format=flowed > >> Content-Transfer-Encoding: 8bit > >> > >> Any suggestions? Thanks > >> > >> _______________________________________________ > >> Kernelnewbies mailing list > >> Kernelnewbies(a)kernelnewbies.org > >> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > What email client did you use to send in your patch? > > I used thuderbird to post to the list. My issue seemed to be not having > the usb: dwc2: tags in the subject line, and my subject being too long. > Both apparently heavily weight the filter towards treating the message > as spam. I also removed anything in the debug information that resembled > a url or email address, which didn't help immediately but might have > helped weight it towards not spam after I did the above things. It > might be a good idea to have a list of suggestions like these on the > wiki. You will find kernel documentation [1] on preferred email clients and formats of interest. Among other things, the advise on the format of email messages is: Don't send patches with ``format=flowed``. This can cause unexpected and unwanted line breaks. My personal preference is the use of 'git send-email'. I've also found mutt to be compliant with the guidelines laid out in the reference doc. Hope this helps. [1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/plain/Docu…

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Linux kernel mailing list filtering issues
by hal＠halemmerich.com July 20, 2018

July 20, 2018

Hi all, I've been trying to post a bug report to the linux-usb mailing list but keep getting trapped in the filters despite ensuring I'm using plaintext. Heres what I get in the bounce back: The mail system <linux-usb(a)vger.kernel.org>: host vger.kernel.org[209.132.180.67] said: 550 5.7.1 Content-Policy accept-into-freezer-1 msg: Bayes Statistical Bogofilter considers this message SPAM. BF:<S 1> In case you disagree, send the ENTIRE message plus this error message to <postmaster(a)vger.kernel.org> ; I've sent the message to the postmaster but haven't heard anything. My message got through to the maintainer, who has requested I fix my message and get it on the mailing list proper but nothing I've tried is working. Heres part of the header from the source of my most recent message: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Any suggestions? Thanks

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Re: mmap with huge page
by David Frank July 18, 2018

July 18, 2018

Thanks Mike. I read the doc, which is not explicit on the non used file taking up huge page count On Tuesday, July 17, 2018, 4:57:04 PM PDT, Mike Kravetz <mike.kravetz(a)oracle.com> wrote: On 07/17/2018 12:05 PM, David Frank wrote: > Hi, > According to the instruction, I have to mount a huge directory to hugetlbfs and create file in the huge directory to use the mmap huge page feature. But the issue is that, the files in the huge directory takes up the huge pages configured through > vm.nr_hugepages = > > even the files are not used. > > When the total size of the files in the huge directory = vm.nr_hugepages * huge page size, then mmap would fail with 'can not allocate memory' if the file to be mapped is in the huge dir or the call has HUGEPAGETLB flag. > > Basically, I have to move the files off of the huge directory to free up huge pages. > > Am I missing anything here? > No, that is working as designed. hugetlbfs filesystems are generally pre-allocated with nr_hugepages huge pages. That is the upper limit of huge pages available. You can use overcommit/surplus pages to try and exceed the limit, but that comes with a whole set of potential issues. If you have not done so already, please see Documentation/vm/hugetlbpage.txt in the kernel source tree. -- Mike Kravetz

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mmap with huge page
by David Frank July 17, 2018

July 17, 2018

Hi,According to the instruction, I have to mount a huge directory to hugetlbfs and create file in the huge directory to use the mmap huge page feature. But the issue is that, the files in the huge directory takes up the huge pages configured throughvm.nr_hugepages = even the files are not used. When the total size of the files in the huge directory = vm.nr_hugepages * huge page size, then mmap would fail with 'can not allocate memory' if the file to be mapped is in the huge dir or the call has HUGEPAGETLB flag. Basically, I have to move the files off of the huge directory to free up huge pages. Am I missing anything here? Thanks, David

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newly add MAP_SYNC flag to mmap
by David Frank July 17, 2018

July 17, 2018

Hi, I installed LTS 18.04 with headers. I'm trying to use the new flag MAP_SYNC with mmap call, but it complained MAP_SYNC undefined.What #define do I need to enable this? Thanks, David

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