Yes, it is. However, this kind of problem happens easily with a Pentium III @ 700Mhz and never with a celeron @1.3Ghz !
Dmitry Adamushko wrote: > Hi, > > do you mean that your rt tasks work fine until you press Ctrl-Alt-FN > to switch virtual terminals? > > well, it's pretty enough information at least to point out the code > that caused a problem in question :) > > it seems to be "sysexit" in entry.S, namely the following block > > /* if something modifies registers it must also disable sysexit */ > EMULATE_ROOT_IRET(sysenter_exit) > movl EIP(%esp), %edx > movl OLDESP(%esp), %ecx > xorl %ebp,%ebp > sti > -> sysexit > > Looking at dumped register values : > > edx == ffffe410 that stands for some code inside "vsyscall page" - > [fffe000, ffff0000]. I suppose the next instruction after "sysenter". > > ecx - a pointer to user-space stack of the task that issued a syscall > through "vsyscall page". it's 0xb7d1223c and at least we may say it > belongs to user-space (but can point to something invalid). > > this is exactly what "sysexit" expects to find in edx and ecx, namely > EIP and ESP. > > Then let's look at the "code": > > Code: 44 24 18 e8 81 ca 03 00 fb 8b 4d 08 66 f7 c1 ff fe 0f 85 4e 01 00 > 00 e8 ed ea 00 00 8b 44 24 18 8b 54 24 28 8b 4c 24 34 31 ed fb <0f> 35 > 50 fc 06 1e 50 55 57 56 52 51 53 ba 7b 00 00 00 8e da 8e > > <0f> 35 seems to be the current instruction and this is an opcode for > "sysexit" on e.g. AMD aa64 (google helps :) > > The following also confirms that: > EIP is at sysenter_exit+0xf/0x11 > > EIP points to last 2 bytes of sysenter_exit and that's "sysexit". > > I tried to find what exactly "sysexit" does and when/why it may fault > but failed so far. e.g. if ecx is wrong (points to non-existent vma). > > It's also interesting that 2 tasks get GPF, both returning from some > syscall. > > Maybe Philippe who (I suppose) introduced sysenter/exit support for > Adeos/ipipe can shed some light. > > _______________________________________________ Xenomai-core mailing list Xenomaifirstname.lastname@example.org https://mail.gna.org/listinfo/xenomai-core