September 2015 - kernelnewbies@kernelnewbies.org

Re: Unset LOCKDEP and TRACE_IRQFLAGS_SUPPORT
by Valdis.Kletnieks＠vt.edu Sept. 27, 2015

Sept. 27, 2015

On Mon, 28 Sep 2015 09:58:21 +1300, vibnwis said: > Thanks for sharing. Being a newbie, I would have to have some sort faith > until it is proven otherwise. Hence, I am tasked to get the TRACE_IRQFLAGS > turn off. Once, I have got it done and the results would tell us if the > patches were fine or not. The fact they may work with a specific option turned off is *not* proof that they are "fine" - merely that it doesn't trip over the problem. It's kind of like being told your car's brakes are possibly defective and you should avoid heavy braking - and your response is to choose a path home that doesn't involve any heavy braking and then saying your brakes are "fine". It's even more worrisome that people are suggesting "just turn it off" without being able to point at a reason *why* it needs to be turned off. Which gives you more confidence: NVidia's modules won't work on a kernel defined with LOCKDEP enables, we don't know why, so just turn it off.. versus NVidia's modules won't work on a LOCKDEP kernel because with that defined, the locking functions called by the module are redirected to debugging LOCKDEP variants that are EXPORT_SYMBOL_GPL. When you try to modprobe it, the _GPL variants aren't available to the NVidia module due to its licensing, so you get 'unresolved symbol' errors. This information should be enough for you to figure out how to fix your personal copy and make it work (but not to make that copy redistributable). See the difference?

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Avoid Camelcase
by Shraddha Barke Sept. 26, 2015

Sept. 26, 2015

What should be done about the "Avoid Camelcase" CHECK detected by checkpatch.pl for patches ? Thanks, Shraddha

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Adding GPIO/SPI/I2C functionality to FTDI driver
by chrysn Sept. 26, 2015

Sept. 26, 2015

Hello kernelnewbies list, I've run into situations where it would be practical to have the GPIO, I2C and SPI functionality some FTDI chips provide as kernel devices. (The chips are more often used as USB serial adapters; only that feature is supported by the current kernel drivers). The presence of an extensive userspace library (libftdi) and the observation of a project in a similar situation[1] that has not made it into the kernel makes me doubt that implementing that in the kernel is the way to go. I've written up more thoughts on this on [2], including exploration of userspace SPI/GPIO/I2C devices (think FUSE / USBIP / uinput), but it boils down to a simple question: Is support for alternative operation modes in FTDI chips something that is welcome and (easily) feasible in the kernel? Best regards chrysn [1] http://danielthesantos.blogspot.co.at/2013/08/why-mcp2210-driver.html [2] http://christian.amsuess.com/idea-incubator/ftdi-kernel-support/ -- You don't become great by trying to be great. You become great by wanting to do something, and then doing it so hard that you become great in the process. -- Marie Curie (as quoted by Randall Munroe)

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[PATCH] 8250_pci: Prevent Exar/RTD Boards from binding.
by Rob Groner Sept. 25, 2015

Sept. 25, 2015

Serial boards made by RTD using the Exar XR17V358 chip rely on the extra capabilities of the Exar-provided driver to allow configuration of the board. When support for the Exar chip was added to the kernel 8250_pci driver, this then prevented easy use of the board by customers for anything other than standard serial usage in RS232 mode. This patch prevents RTD sub-vendor boards from being bound by the 8250_pci driver, if it uses the XR17V358 chip. Other RTD boards using Exar chips are not affected. Signed-off-by Rob Groner <rgroner(a)rtd.com> --- drivers/tty/serial/8250/8250_pci.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index 68042dd..89baf7f 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -359,6 +359,16 @@ static void pci_ni8430_exit(struct pci_dev *dev) iounmap(p); } +/* + * RTD Embedded Technologies, Inc. boards + * Prevent from being bound to 8250 driver + */ +static int +pci_xr17v35x_rtd_probe(struct pci_dev *dev) +{ + return -ENODEV; +} + /* SBS Technologies Inc. PMC-OCTPRO and P-OCTAL cards */ static int sbs_setup(struct serial_private *priv, const struct pciserial_board *board, @@ -2105,6 +2115,8 @@ pci_wch_ch38x_setup(struct serial_private *priv, #define PCI_DEVICE_ID_PERICOM_PI7C9X7954 0x7954 #define PCI_DEVICE_ID_PERICOM_PI7C9X7958 0x7958 +#define PCI_SUBVENDOR_ID_RTD 0x1435 + /* Unknown vendors/cards - this should not be in linux/pci_ids.h */ #define PCI_SUBDEVICE_ID_UNKNOWN_0x1584 0x1584 #define PCI_SUBDEVICE_ID_UNKNOWN_0x1588 0x1588 @@ -2608,6 +2620,14 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = { { .vendor = PCI_VENDOR_ID_EXAR, .device = PCI_DEVICE_ID_EXAR_XR17V358, + .subvendor = PCI_SUBVENDOR_ID_RTD, + .subdevice = PCI_ANY_ID, + .probe = pci_xr17v35x_rtd_probe, + .setup = pci_xr17v35x_setup, + }, + { + .vendor = PCI_VENDOR_ID_EXAR, + .device = PCI_DEVICE_ID_EXAR_XR17V358, .subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID, .setup = pci_xr17v35x_setup, -- 1.9.1

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error when make pdfdocs
by 慕冬亮 Sept. 25, 2015

Sept. 25, 2015

I git clone and git pull the latest linux kernel. When I make pdfdocs, it reports the following error to me. But I checked the filesystems.xml:14946, no error found. ----------------------------------------------------------------------------------------------- PDF Documentation/DocBook/filesystems.pdf Using catalogs: /etc/sgml/catalog Using stylesheet: /usr/share/docbook-utils/docbook-utils.dsl#print Working on: /home/mdl/Repos/linux/Documentation/DocBook/filesystems.xml openjade:/home/mdl/Repos/linux/Documentation/DocBook/filesystems.xml:14946:16:E: end tag for "variablelist" which is not finished Documentation/DocBook/Makefile:131: recipe for target 'Documentation/DocBook/filesystems.pdf' failed make[1]: *** [Documentation/DocBook/filesystems.pdf] Error 8 Makefile:1339: recipe for target 'pdfdocs' failed ----------------------------------------------------------------------------------------------- - mudongliang

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Which git for developing patch?
by Rob Groner Sept. 24, 2015

Sept. 24, 2015

I am developing a patch for the 8250_pci.c file. Looking at the MAINTAINERS file for 8250 serial, it listed a git repo so I checked that out and figured that was what I should make it from. However, it won't build for me (openssl/bio.h is missing) after a cloning. Am I supposed to use the git repo shown in the MAINTAINERS file (git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git) or some different one for making a patch for a serial file? Thank you. Rob Groner Software Engineer Level II

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Active Memory never reclaimed please help me understand
by Prem Kumar Sept. 24, 2015

Sept. 24, 2015

Dear All, I have done quite a bit of reading on Active memory reported in /proc/meminfo and in short says it is never reclaimed unless absolutely necessary, and it caches the recently used files/pages in memory. Although I fail to understand the consequences that I face here. I have disk-less and swap-less nodes. So all I have to do, is play with the RAM on the box. Issue that brought me here is investigating why after running some applications, used memory is never available for use with any other applications. In other words I cannot run any programs that requests memory more than what is shown as free in the output of free command and MemFree in the output of the cat /proc/meminfo For example if I ran any program that requires more than 6GB on the first node below and more than 1GB on the second node below they fail instantly, and work fine if within the limist of free. There is nothing else running on the system other than system processes/services. total used free shared buffers cached Mem: 23 17 6 0 0 9 -/+ buffers/cache: 8 15 Swap: 0 0 0 total used free shared buffers cached Mem: 23 22 1 0 0 0 -/+ buffers/cache: 21 1 Swap: 0 0 0 Since the applications that ran previously are not running any more "even though they died out of memory because they requested more memory than available", shouldn't the OS see that any memory used previously as useless and can it not reclaim that for use with the next job/program on that machine. On every machine that I have run into this problem the out put of /proc/meminfo shows that Active memory is used up the amount shown in the free command and limits my further runs. This is driving me insane and making me feel stupid knowing that OS is smart enough to handle this, then what am I missing here to understand? Please advise. Appreciate any insight into this. Best Regards, Prem

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getting warning when a method parameter in a kernel module is not used
by Kevin Wilson Sept. 24, 2015

Sept. 24, 2015

Hi, When a method parameter in a kernel module is not used, we do not get any warning (as opposed to a variable which is not used). Is there any compilation flag which enables getting warning in such a case ? Regards, Kevin

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Question about "Creating first patch" guide
by Rob Groner Sept. 24, 2015

Sept. 24, 2015

The OutreachyfirstpatchSetup has been very helpful in setting up my computer to develop a patch to submit to the kernel overlords. I'm at the point where I've changed the kernel code, ran and test it, and see just my changes with "git diff". What has me a little confused is that before I actually create the patch file (to submit to the appropriate mailing list), it says to actually commit the change. Perhaps I don't understand how git handles commit (I primarily use svn), but it seems like actually committing the change is kind of presumptuous before even posting anything on the mailing list of those that control the git repository. What part am I not understanding? Thank you. Rob Groner

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Issue using kernel linked list in user space
by Gunjan Mehta Sept. 21, 2015

Sept. 21, 2015

I have a linked list like this http://pastebin.com/bwF3jLb6 . The problem i am facing is i have initialized the list head and then i am doing malloc for that struct object. What i need is i want to make struct abc_st *r as head of linked list and other nodes after it. typedef struct abc { char client_id[18]; char mac[18]; st_list_head list; }abc_st; abc_st* check_fields (abc_st *ptr) { char cmd[500]; MYSQL_RES *result; MYSQL_ROW row; int num_rows; abc_st *r=NULL,*temp=NULL; INIT_LIST_HEAD(&r->list); // i have intialized the head here sprintf(cmd, "SELECT * FROM ABCD_TABLE WHERE MAC = %.4x", ptr->mac); /* Running the sql query to check for fields with value in database */ if (mysql_query(abc_db.db_handle, cmd)) { num_rows = -1; goto done; } result = mysql_store_result(abc_db.db_handle); if (result == NULL) { num_rows = -1; goto done; } num_rows = mysql_num_rows(result); while ((row = mysql_fetch_row(result))) { r= (abc_st *)malloc(sizeof(abc_st)); memcpy(r->mac,row[1],strlen(row[1])+1); memcpy(r->client_id,row[0],strlen(row[0])+1); How should i use list_add ? //list_add(struct list_head *new, struct list_head *head) //prototype of list_add // list_add(&temp->list,&r->list); //it will go wrong here, i want to make r(structure r as head and then add other strutcure objects) // r->link = NULL; //list_add(r, ptr); } done: mysql_free_result(result); return r; }

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