Jun Koi wrote: > On Wed, Jun 16, 2010 at 4:49 PM, Jan Kiszka <jan.kis...@web.de> wrote: >> Jun Koi wrote: >>> On Wed, Jun 16, 2010 at 4:40 PM, Jan Kiszka <jan.kis...@web.de> wrote: >>>> Jun Koi wrote: >>>>> On Wed, Jun 16, 2010 at 4:07 PM, Alfredo Mungo <chimerane...@gmail.com> >>>>> wrote: >>>>>> Same thing happens to me, same versions as above.. I must turn to >>>>>> another app to accomplish my work while awaiting for a bug-fix, the code >>>>>> is perfectly executed but while gdb hits the breakpoints qemu goes on.. >>>>>> >>>>>> -- >>>>>> qemu doesn't stop execution upon hitting a breakpoint >>>>>> https://bugs.launchpad.net/bugs/581353 >>>>>> You received this bug notification because you are a member of qemu- >>>>>> devel-ml, which is subscribed to QEMU. >>>>> i think this bug has been fixed in 0.12.4. have you tried that?? >>>> Or this is a well-known gdb deficit: if the bootloader operates in >>>> real-mode, you have to set two breakpoints, one at the linear address to >>>> make qemu catch it, and another one at the segment offset to avoid gdb >>>> skipping the exit due to ip != bp-addr. >>>> >>>> gdb is still fairly restricted when it comes to system-level debugging, >>>> specifically as it lacks support for special x86 registers and the >>>> segmented addressing mode. >>> what do you mean by "it lacks support for special x86 registers" ? >> idtr, gdtr, ldtr, tr, crX - to name the most important ones. > > do you mean gdb has no command to show the values of these registers? > or you mean it doenst have anyway to get notified when these registers > are modified? (i dont see how this is useful for debugging, anway)
Both: Neither supports gdb them as part of its register set nor does the remote gdb protocol transport them. You need this for segmented addressing, either in real mode (linear address = segment * 16 + offset) or in segmented protected mode (less common in modern OSes, but at least still used for per-CPU variables in Linux). And you need a way to detect the current operation mode at all to switch between 16/32, and 64 bit registers (set arch i386 vs. i386:x86-64). You don't need all this for application-level debugging, and that's why gdb lacks it so far. Jan
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