I'm using 2.4.21 kernel (and also tried 2.6.18 with the same behavior). the memory address is being written through a kernel module . please see below :
[0]kdb> md 0xa0f7bc94 0xa0f7bc94 00000000 00000001 00000003 00000000 ................ [0]kdb> bpha 0xa0f7bc94 dataw 4 [0]kdb> go the breakpoint is not called even though the memory address being changed: [0]kdb> md 0xa0f7bc94 0xa0f7bc94 00000064 00000001 00000003 00000000 d............... jidong xiao wrote: > On Wed, May 7, 2008 at 2:41 PM, Avi Nehori <[EMAIL PROTECTED]> wrote: > >> Thanks for your reply Jay, >> I'm running i386 and the thing is that when i set the breakpoint on a >> memory address(trying to catch a memory >> corruption bug) the watch point is not getting hit when the memory is >> written. >> I'm following the kdb documentation which says : >> >> "The |bph| and |bpha| commands can be used (provided the architecture >> supports use of hardware registers) to apply read and write breakpoints. >> This means we can get control whenever data is read from or written into >> a particular address. This can be extremely handy when debugging >> data/memory corruption problems, where you can use it to identify the >> corrupting code/process." >> >> *Examples* >> >> *To enter the kernel debugger whenever four bytes are written into >> address 0xc0204060:* >> | [0]kdb> bph 0xc0204060 dataw 4 >> >> >> so i followed the documentation and set a breakpoint using bph (and >> also bpha) on a memory address >> exactly as the above example ,but when i modify the memory address >> ,the breakpoint does not hit.... >> any idea what is wrong here ? >> any help will be very appreciated . >> Thanks! >> >> > > What the kernel version are you using? and how do you modify the memory > address? > > Regards > Jason Xiao > > >> || >> >> >> || >> | >> >> >> >> >> Jay Lan wrote: >> >>> Avi Nehori wrote: >>> >>> >>>> Hi, >>>> I'm trying to set a watch point with bpha as follows : >>>> bpha address dataw 4 >>>> but the watchpoint is never called when the memory address is changed. >>>> is it a know bug ? >>>> is there a patch ? >>>> >>>> >>> I heard bph/bpha worked on x86_64. However, hardware breakpoint >>> was not implemented on IA64. Were you on IA64? >>> >>> Greg Banks of SGI ([EMAIL PROTECTED]) provided patches for IA64. Many >>> thanks to Greg! >>> 1) gnb-kdb-implement-bpha-v3 >>> This patch implemented bph/bpha on IA64. >>> 2) gnb-test-kdb-bph >>> This patch provided a test infrastructure to test all the ia64 >>> data* breakpoint features. >>> >>> I have uploaded the patches to the download area. >>> ftp://oss.sgi.com/projects/kdb/download/v4.4 >>> >>> >>> Cheers, >>> - jay >>> >>> >>> >>>> Thanks. >>>> --------------------------- >>>> Use http://oss.sgi.com/ecartis to modify your settings or to unsubscribe. >>>> >>>> >>> >>> Scanned by Check Point Total Security Gateway. >>> >>> >> --------------------------- >> Use http://oss.sgi.com/ecartis to modify your settings or to unsubscribe. >> >> > > Scanned by Check Point Total Security Gateway. > > --------------------------- Use http://oss.sgi.com/ecartis to modify your settings or to unsubscribe.
