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compile kernel
by esmaeil mirzaee Sept. 10, 2011

Sept. 10, 2011

Hi all I apologize for weak English and speaking ambiguously. I download Linux kernel and I love to learn about it. I try to compile a file like ~/kernel/acct.c but I've got error anyone can help me. $ gcc acct.c -o ac acct.c:46: fatal error: linux/mm.h: No such file or directory compilation terminated.

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how diff between hardlink trees works?
by Vaibhav Jain Sept. 10, 2011

Sept. 10, 2011

Hi, I am not able to understand how diff between two trees of which one is just contains hardlinks to another's files (cp -al )ing works.I am asking this question here because I need to build a custom kernel for which I need to generate patch. So the documentation suggests to create a hardlink copy of the kernel source tree using cp -al and then make changes to one of the trees and run a diff.I am wondering that if files are hardlinks then changes to one copy will affect another in which case diff should give no output. Also, the patch I created looks a little odd as it contains complete modified files instead of just the differences. Please help! Thanks Vaibhav Jain

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Re: compile kernel
by esmaeil mirzaee Sept. 9, 2011

Sept. 9, 2011

Thank you for reply On Fri, Sep 9, 2011 at 4:55 AM, Pelle Windestam <pelle(a)windestam.se> wrote: >> >> $ gcc acct.c -o ac >> acct.c:46: fatal error: linux/mm.h: No such file or directory >> compilation terminated. >> > > That is because gcc does not know where to look for the included > mm.h-file, the gcc compiler needs to be specifically told where to > look for include files if they are not in the standard directories. > You can do that by passing it the -I option followed by the directory > to look in. You mean I must put the address of library when I try to compile if yes. ~/linux-2.6.39.3/kernel the file is in this place (acct.c). Could you give me form of compile command it can be like this gcc -i ~/linux-2.6.39.3/kernel acct.c -o acct esmaeil

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pci_request_regions erring out
by Giriprasad Deviprasad Sept. 9, 2011

Sept. 9, 2011

Hi All, I am currently working on the realtek driver available in http://linuxgazette.net/156/jangir.html. When I run the driver, pci_request_regions is erring out as : Device enabled ---------------------------------------------------------------- Base 0 Starting Address = 9c00 End Address = 9cff Length = 256 This Port is I/O mapped. It is NON Prefetchable.This is readable and writable. Base 0 starting Address = 9c00 End Address = 9cff Length = 256 resource is not available Base 1 Starting Address = fdaff000 End Address = fdaff0ff Length = 256 This Port is Memory mapped. It is NON Prefetchable. This is readable and writable. Reading the PCI BAR registers Checking the PCI BAR registers for Memory mapped flag Calling pci_request_region 8139too 0000:04:03.0: BAR 0: can't reserve I/O region [0x9c00-0x9cff] Could not get PCI region sys_init_module: 'real3'->init suspiciously returned 1, it should follow 0/-E convention sys_init_module: loading module anyway... I am attaching the driver code. Any clues as to why? Thanks & Regards, D.Giriprasad

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adding preprocessor defines in module makefiles
by Christopher Harvey Sept. 9, 2011

Sept. 9, 2011

Hi, I'm trying to build a kernel module for fun, and I can't figure out a clean way to add preprocessor defines that correspond to Kconfig values. I'm trying to set CONFIG_SND_DEBUG specifically. My module has only one file, and I've tried adding #define CONFIG_SND_DEBUG as the first line in the .c file, but now I'm getting the following warning: WARNING: "__snd_printk" [/home/chris/snd/snd-foo.ko] undefined! I haven't compiled the kernel running on my system with the CONFIG_SND_DEBUG option but I haven't been able to see a reason why that should change anything for my module. thanks, Chris

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Re: Why the PF_SUPERPRIV flag is cleared?
by rohan puri Sept. 9, 2011

Sept. 9, 2011

Hi, When forking a child process, the copy_process() function will by default clear the PF_SUPERPRIV flag, which indicates whether a process use superuser privileges. That means a superuser process will create a child process does not has superuser privileges. I think the child process of a superuser process should also be a superuser one, while the child process of a normal process by default should also be a normal one (except that the setuid bit of the child executable is turn on). In both cases it is not necessary that the PF_SUPERPRIV flag to be cleared. So, I wonder why the PF_SUPERPRIV flag is cleared by defult. Hi, This flag PF_SUPERPRI, indicates used superuser privileges and not use superuser privileges. Which in any case, INDEPENDENT of all the processes which have superuser privileges, whether they had used them or not and for those processes which do not have superuser privileges needs to be cleared for the child of them (since the child process has been just created and at this point in time it has not used the superuser privileges) Its a kind of initialization you can think of. Regards, Rohan.

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2 mods with same PCI-ID table, one installs, other fails modprobe
by Jim Cromie Sept. 8, 2011

Sept. 8, 2011

(aside - whats the correct ML? Ive used both suggested by my mail interface) I have 2 modules with same modinfo alias, one installs, the other gets -ENODEV. Id expect them to both act the same. What am I missing ? root@voyage:~# modprobe geode-aes root@voyage:~# lsmod |grep geode_aes geode_aes 4229 0 root@voyage:~# modprobe geode-rng dynamic_debug:ddebug_remove_module: removing module "geode_rng" FATAL: Error inserting geode_rng (/lib/modules/3.0.0-skc-dyndbg+/kernel/drivers/char/hw_random/geode-rng.ko): No such device root@voyage:~# modinfo geode-aes filename: /lib/modules/3.0.0-skc-dyndbg+/kernel/drivers/crypto/geode-aes.ko license: GPL description: Geode LX Hardware AES driver author: Advanced Micro Devices, Inc. alias: pci:v00001022d00002082sv*sd*bc*sc*i* depends: vermagic: 3.0.0-skc-dyndbg+ preempt mod_unload modversions GEODEGX1 root@voyage:~# modinfo geode-rng filename: /lib/modules/3.0.0-skc-dyndbg+/kernel/drivers/char/hw_random/geode-rng.ko license: GPL description: H/W RNG driver for AMD Geode LX CPUs alias: pci:v00001022d00002082sv*sd*bc*sc*i* depends: rng-core vermagic: 3.0.0-skc-dyndbg+ preempt mod_unload modversions GEODEGX1 IE both have same alias, and (unsurprisingly) the same DEVICE_ID. geode-rng's 1 dependency isnt the problem: root@voyage:~# modprobe rng-core root@voyage:~# lsmod |grep rng rng_core 3010 0 DEVICE-IDs: jimc@chumly:~/projects/lx/linux-2.6/drivers/crypto$ grep PCI_DEV geode-aes.c { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), } , jimc@chumly:~/projects/lx/linux-2.6/drivers/crypto$ cd ../char/hw_random/ jimc@chumly:~/projects/lx/linux-2.6/drivers/char/hw_random$ grep PCI_DEV geode-rng.c { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), 0, }, hmmm. is that trailing 0 important ? Id think not, {..} is a literal constant assignment, 0 is only sensible default. The apparent diff is how the __init is done. static struct pci_device_id geode_aes_tbl[] = { { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), } , { 0, } }; MODULE_DEVICE_TABLE(pci, geode_aes_tbl); static struct pci_driver geode_aes_driver = { .name = "Geode LX AES", .id_table = geode_aes_tbl, .probe = geode_aes_probe, .remove = __devexit_p(geode_aes_remove) }; static int __init geode_aes_init(void) { return pci_register_driver(&geode_aes_driver); } geode-rng does it the (older?) more manual way: static int __init mod_init(void) { int err = -ENODEV; struct pci_dev *pdev = NULL; const struct pci_device_id *ent; void __iomem *mem; unsigned long rng_base; for_each_pci_dev(pdev) { ent = pci_match_id(pci_tbl, pdev); if (ent) goto found; } /* Device not found. */ goto out; found: ... Qs 1 - why do they differ in modprobe results ? bug likely ?? 2 - which is correct ? success or failure ? FWIW, heres my PCI devices. The CPU is an SC1100 - its a Geode, but not a Geode-GX or LX (though the distinctions arent as clear as Id like :-/) root@voyage:~# lspci -nn 00:00.0 Host bridge [0600]: Cyrix Corporation PCI Master [1078:0001] 00:06.0 Ethernet controller [0200]: National Semiconductor Corporation DP83815 (MacPhyter) Ethernet Controller [100b:0020] 00:07.0 Ethernet controller [0200]: National Semiconductor Corporation DP83815 (MacPhyter) Ethernet Controller [100b:0020] 00:08.0 Ethernet controller [0200]: National Semiconductor Corporation DP83815 (MacPhyter) Ethernet Controller [100b:0020] 00:0a.0 Ethernet controller [0200]: Belkin Wireless PCI Card - F5D6001 [1799:6001] (rev 20) 00:0e.0 Ethernet controller [0200]: Marvell Technology Group Ltd. 88W8361 [TopDog] 802.11n Wireless [11ab:2a02] (rev 03) 00:12.0 ISA bridge [0601]: National Semiconductor Corporation SC1100 Bridge [100b:0510] 00:12.1 Bridge [0680]: National Semiconductor Corporation SC1100 SMI & ACPI [100b:0511] 00:12.2 IDE interface [0101]: National Semiconductor Corporation SCx200, SC1100 IDE controller [100b:0502] (rev 01) 00:12.5 Bridge [0680]: National Semiconductor Corporation SC1100 XBus [100b:0515] 00:13.0 USB Controller [0c03]: Compaq Computer Corporation ZFMicro Chipset USB [0e11:a0f8] (rev 08) Specifically, theres no AMD ID in the output root@voyage:~# lspci -nn |grep 1022 root@voyage:~# lspci -nn |grep 100b 00:06.0 Ethernet controller [0200]: National Semiconductor Corporation DP83815 (MacPhyter) Ethernet Controller [100b:0020] >From all this, it seems that the failure to install is correct, which suggests some bug in pci_register_driver, but its hard to imagine that - otherwize its survived (well hidden) for a long time

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Filesystem allocation bitmap
by Kai Meyer Sept. 8, 2011

Sept. 8, 2011

Is there a generic filesystem method to retrieve the filesystem's allocation bitmap? I'm mostly interested in Ext filesystems, so if there's nothing generic, I'm happy with a specific solution for just Ext. If the answer is "read https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout and then read the bitmaps directly from disk", I think I can deal with that too. -Kai Meyer

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Query about custom fedora build process
by Vaibhav Jain Sept. 8, 2011

Sept. 8, 2011

Hi, I am trying to build a custom fedora kernel on a fedora (FC15) machine by reading the article: http://fedoraproject.org/wiki/Building_a_custom_kernel but i am unable to make any progress as my changes are not getting reflected. So I have query about the procedure given in the article. The article asks to first create hardliks between files in .new and .orig directories and then to make changes and to .new directory and to generate a patch by a diff between the .orig and .new directories. But I am just wondering if the files in both the directories are hardlinks then how can diff work because after changing a file in .new directory the file in .orig directory should also change. cp -r ~/rpmbuild/BUILD/kernel-2.6.$ver.$fedver/linux-2.6.$ver.$arch ~/rpmbuild/BUILD/kernel-2.6.$ver$fedver.orig cp -al ~/rpmbuild/BUILD/kernel-2.6.$ver.$fedver.orig ~/rpmbuild/BUILD/kernel-2.6.$ver.$fedver.new cd ~/rpmbuild/BUILD diff -uNrp kernel-2.6.$ver.$fedver.orig kernel-2.6.$ver.$fedver.new > ../SOURCES/linux-2.6-my-new-patch.patch Thanks Vaibhav Jain

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Doubt regarding asmlinkage
by rohan puri Sept. 8, 2011

Sept. 8, 2011

Hi All, asmlinkage is used in front of the each system call prototype. For x86 arch it indicates that the the parameters are on stack instead of the registers and for x86_64 arch the parameters are in registers only. Doubt i have is whats the need for 32-bit intel arch to put parameters on stack and not registers in a way similar to x86_64? Regards, Rohan.

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