Hi Nico, Thanks for your reply.
On Fri, Mar 19, 2021 at 07:03:59PM +0100, Nico Huber wrote: > Hello Himanshu, > > On 19.03.21 17:12, Himanshu Chauhan wrote: > > On Fri, Mar 19, 2021 at 09:33:43PM +0530, Himanshu Chauhan wrote: > >> Hi, > >> > >> I am working on a hypervisor and running coreboot as guest. > >> During a VMExit, I am seeing coreboot RIPs. Since coreboot > >> is mix of 16-bit/32-bit code and because of relocations, > >> I not able to find the listing of the code at specific address. > >> > >> For example, address is: 0x7f37806 > >> > >> I want to attach the coreboot binary to GDB and then do > >> list *0x7f37806 > > there is almost no 16-bit code in coreboot. I guess we can ignore > it for this matter. What is most important for coreboot addresses > is the stage that is running. On x86, bootblock and romstage run > XIP (execute in-place) from the BIOS ROM which is mapped directly > below the 4GiB line. ramstage is relocated at runtime into RAM, > which I assume is the address you see. Somewhere in the console > output of coreboot it should print the relocation offset. As this > is decided at runtime, I don't know any better way to obtain it. > > When you know the offset it's a matter of loading > build/cbfs/fallback/ramstage.debug > into GDB and telling it the offset (alas, I don't remember the > command but I'm rather sure that it worked once). > > >> > > > > BTW, I can see the post code of 0xf8. Does this mean that > > coreboot is done booting and its trying to load SeaBIOS? > > I see a CPUID request of 0x40000000. I can't see such request > > anywhere in coreboot. But there is one in SeaBIOS, to detect > > if its running on KVM. > > > > I see that the RIP changes from > > 0x7f37827 to 0xf289e > > Indeed this looks like a transition from ramstage to SeaBIOS. 0xf289e > is in the legacy f-segment that is reserved for BIOS code. > Sure. This helps! Just one more question, How is SeaBIOS boot as payload of coreboot different than it booting directly? Regards Himanshu > Hope that helps, > Nico _______________________________________________ coreboot mailing list -- coreboot@coreboot.org To unsubscribe send an email to coreboot-le...@coreboot.org
