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l4linux and sysenter
by Ryan Brown 24 Apr '13

24 Apr '13

Thanks for the ptrace fix, that really helped with debugging. We were seeing programs crash at the first system call when using some versions of glibc, but not others. It seems the difference is that the working glibc's are compiled without vdso support. When glibc tries to use the vdso for system calls, it crashes at the sysenter instruction. If we start l4linux with vdso32=0, the program is able to run. Is sysenter expected to work under l4linux? It looks like it requires using msr's, so perhaps l4linux isn't able to setup sysenter? Should it be installing the int80 vdso function instead? While investigating the vdso stuff to I also became curious. How difficult would it be to set up an l4 specific vdso? I assume just using l4 ipc directly would be more efficient than using int80? Thanks, Ryan Brown

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How to start 2 or more VMs
by Chao-Jui Chang 18 Apr '13

18 Apr '13

Hi hackers, Is there any document that describes how to start 2 or more VMs on Fiasco.OC ? Is it possible to switch consoles between VMs ? Could you point out the direction to me? Thanks, Chao-Jui

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Question about L4/Fiasco
by Samir Boulhram 17 Apr '13

17 Apr '13

Hello, I'm trying to change the scheduler of the L4/Fiasco. I'm aim is to make an RM scheduler policy for schedule 3 VMs. My problem is that I don't have any idea of where I have to start my work. Can you help me please ? -- Kind regards, Samir B.

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l4re compilation order
by gaober 16 Apr '13

16 Apr '13

hi! i have some doubt about the buliding of l4re.who decides the order of the l4re pkg complie?if i want to make pkg drivers earliear than pkg input,hao can i do? does the /pkg/XXX/Control mean anything? and in the obj directory, there are .pc files like libdrivers-input.pc etc.what do they work? Wilbert Gao

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Ring 0 task
by Daniel Waddington - SISA 15 Apr '13

15 Apr '13

Hi, How do you create ring 0 tasks with Fiasco.OC? (I want them to execute rdmsr/wrmsr) Thanks Daniel

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ptrace
by Ryan Brown 15 Apr '13

15 Apr '13

Are there issues using ptrace under l4linux? I'm trying to debug a process using gdbserver, but when I use stepi (PTRACE_SINGLESTEP) it seems to run until the next system call. Has anyone else seen this? Is there some way to use the fiasco debugger to debug an l4linux process?

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RCU performance
by Christian Prochaska 11 Apr '13

11 Apr '13

Hello, when building Fiasco.OC with multiprocessor support enabled, the unmapping of an IPC gate via 'l4_task_unmap()' appears to require at least 3 timer interrupts to occur until completion, which can make a noticable difference in overall execution time compared to the uniprocessor configuration (extreme example: https://github.com/genodelabs/genode/issues/712, in a more realistic scenario (compiling an application) the difference was still like ~2 minutes execution time with the uniprocessor configuration vs. ~6 minutes with the multiprocessor configuration). I've attached the debug output I got while trying to understand what's going on and which shows some of the RCU-related activities after each of the 3 timer interrupts (patch used for the debug messages: https://github.com/cproc/foc/commit/fa7b6f823cb29c0fc1db389ceb956d554d9e154…) According to these messages, the quiescent period had ended after the second timer interrupt and I wonder if it is really necessary to wait for a third timer interrupt before executing the corresponding callbacks. Would it work correctly with the attached patch, too? Christian

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compile l4 source files: idl-parser-driver.hh:62:1: error
by yuqing wang 09 Apr '13

09 Apr '13

Hi, when I compile TUDOS/lEnv tree downloaded form svn.tudo.org , many errors apear in /todu/dice/src/parser/idl: {{{ g++ -DHAVE_CONFIG_H -I. -I. -I../../.. -I../../../src -Wall -I../../../src -g -O2 -MT idl-parser.tab.o -MD -MP -MF .deps/idl-parser.tab.Tpo -c -o idl-parser.tab.o idl-parser.tab.cc In file included from idl-parser.yy:109:0: idl-parser-driver.hh:62:1: error： ‘token_type’ in ‘class yy::idl_parser’ does not name a type idl-parser.tab.cc: in function‘virtual int yy::idl_parser::parse()’: idl-parser.tab.cc:352:42: error： ‘idllex' not declared in this scope make[7]: *** [idl-parser.tab.o] Error 1 make[7]: Leaving directory ‘/todu/dice/src/parser/idl’ make[6]: *** [all-recursive] Error 1 make[6]: Leaving directory ‘todu/dice/src/parser’ }}} Any help is appreciated yuqing wang

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L4android mlock on vectors page causes unresolvable page fault
by Matthias Petschick 08 Apr '13

08 Apr '13

Hello, while experimenting with lvm, I noticed that mlocking the vectors page at 0xbffff000 from user space causes an unresolvable page fault (see full trace below). In particular, the lvcreate process attempts to lock its mapped memory regions when activating a volume, which includes the vectors page. While debugging this, I further noticed that L4android maps the vectors page to 0xbffff000 by default instead of 0xffff0000, configurable via CONFIG_VECTORS_BASE, however references to the hard-coded address 0xffff0000 remain in some places under arch/l4, e.g. in devicemaps_init() in arch/l4/mm/arch-arm/mmu.c. Without further investigating how the vectors page addressing is treated in L4android, I cannot say whether this is related or not. The pc in the backtrace is in special_mapping_fault, apparently because the vma for the vectors page was installed with a NULL pointer for its pages array, hence vm_private_data is also NULL when dereferenced by special_mapping_fault in if (*pages). The oops itself seems to be triggered because pfa is 0x1 and l4x_handle_pagefault refuses to resolve pagefaults for addresses < L4_PAGESIZE. Here's the associated trace: Page fault (non-resolved): pfa=1 pc=108df14 Internal error: Boom!: 410007 [#5] SMP Modules linked in: CPU: 0 Tainted: G D W (3.1.10-l4-dirty #8) PC is at special_mapping_fault+0x80/0xe0 LR is at __do_fault+0x68/0x464 pc : [<0108df14>] lr : [<01088b50>] psr: 6000001f sp : 132dbda8 ip : 00000000 fp : 0bd4eff8 r10: 00000000 r9 : 0137a1ac r8 : 00000008 r7 : 00000000 r6 : bffff000 r5 : 0605ae20 r4 : 01d38288 r3 : 000bffff r2 : 000bffff r1 : 132dbdc8 r0 : 00000000 Flags: nZCv IRQs on FIQs on Mode SYS_32 ISA ARM Segment user Process lvcreate (pid: 395, stack limit = 0x132da2f0) Stack: (0x132dbda8 to 0x132dc000) bda0: 014e54a0 00000000 01d38288 01088b50 000284d0 01fa6cc0 bdc0: 132da000 01fa6700 00000008 000bffff bffff000 00000000 014a8e20 00000000 bde0: 01d38288 00000008 0bd4eff8 060d97fc 0605ae20 000bffff 00000000 0108bfb8 be00: 000bffff 00000008 00000000 01600000 014c60e0 bffff000 0bd4c000 0605ae20 be20: 000005ff 0bd4eff8 01d38288 00000008 00000000 0108c138 0bd4eff8 00000008 be40: 00000052 01d38288 01fa6cc0 bffff000 0605ae20 132dbedc 0605ae20 0108c34c be60: 132da000 00000000 00000001 00000010 00000000 00000000 014cf754 bffff000 be80: 00000001 01d382a0 0605ae20 132dbedc 00000001 0605ae20 0605ae58 0108cff4 bea0: 00000052 00000000 00000000 132dbedc 0605ae5c 01d38288 c0000000 c0000000 bec0: bffff000 0108d068 132dbedc 132da000 00001000 00000000 00000000 00000001 bee0: 0605ae5c 00000096 bffff000 0108d8f0 00001000 0000a790 000ed0d7 00001000 bf00: 132da000 0100f854 00001000 000ed0d7 00000000 00000000 00000000 40095068 bf20: 132da000 132dbfb0 01fa6cc0 132da000 014ec0e8 133ea36c 00000000 0bec6000 bf40: 00000000 00000000 00000000 00000000 00000000 01195d88 00000000 68732363 bf60: 00000000 00000000 00000000 00000000 01fa6cc0 01fa6cc0 b3000c00 132da000 bf80: b3000e00 ef000000 00000000 f1886fb8 ffff0200 60000010 0100d84c b3000c00 bfa0: 000ed0b3 f1886fec 000ba4c8 00079560 bffff000 00001000 0000a790 000c681c bfc0: 00001000 000ed0d7 000bc08c 00000096 00000072 000ed0b3 000ad844 000ba4c8 bfe0: 000bc0e0 bf87c608 00079560 40191234 60000010 bffff000 00000000 00000000 [<0108df14>] (special_mapping_fault+0x80/0xe0) from [<01088b50>] (__do_fault+0x68/0x464) [<01088b50>] (__do_fault+0x68/0x464) from [<0108bfb8>] (handle_pte_fault+0xb0/0x1a0) [<0108bfb8>] (handle_pte_fault+0xb0/0x1a0) from [<0108c138>] (handle_mm_fault+0x90/0xc0) [<0108c138>] (handle_mm_fault+0x90/0xc0) from [<0108c34c>] (__get_user_pages+0x12c/0x2f8) [<0108c34c>] (__get_user_pages+0x12c/0x2f8) from [<0108cff4>] (__mlock_vma_pages_range.clone.2+0x78/0x80) [<0108cff4>] (__mlock_vma_pages_range.clone.2+0x78/0x80) from [<0108d068>] (do_mlock_pages+0x6c/0x148) [<0108d068>] (do_mlock_pages+0x6c/0x148) from [<0100f854>] (l4x_vcpu_entry_c+0xc74/0x1f90) [<0100f854>] (l4x_vcpu_entry_c+0xc74/0x1f90) from [<00079560>] (0x79560) Code: e1a02003 e1a0c003 e2400001 1afffff3 (e59c4000) ---[ end trace 47d173d365d03980 ]--- Segmentation fault Maybe someone with a better understanding of how L4android treats the vectors page has an idea what's going wrong here? Cheers, Matthias

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How to access SD card on ARM board
by Chao-Jui Chang 08 Apr '13

08 Apr '13

Hi hackers, I want to use SD card as root file system for L4Linux. Base on my understand, we can use IO assignment in libio and let L4Linux kernel to access the devices directly. If this is correct, then next we need to choose correct driver in L4Linux's config menu. However, some device is platform specific, for example, "SDHCI support on Samsung S3C SoC" requires PLAT_SAMSUNG. This option is not available in L4Linux config menu. I have tried to modify the dependence in kernel's Kconfig, but it results in lots of compiler error, such as missing header files. Is this the correct way to achieve my goal? Or I need to make the driver as part of l4re ? Thanks, Chao-Jui

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