On Tue, Jan 09, 2018 at 02:02:52PM -0500, Stefan Berger wrote: > On 01/09/2018 10:14 AM, Kevin O'Connor wrote: > > On Tue, Jan 09, 2018 at 10:00:44AM -0500, Stefan Berger wrote: > > > is it possible to save a few bytes, a pointer, across a reboot? I have > > > tried to do this by allocating a memory chunk in the fsegement and storing > > > the pointer there surrounded by 2 'magic' 32 bit values. When trying to > > > find > > > the magic values on reboot early in handle_post() it doesn't seem to find > > > them anymore. Is there another memory segment where SeaBIOS could store > > > the > > > few bytes and find them again? > > Didn't you have that implemented with the "Support Physical Presence > > Interface Spec" patches you made back in 2015? > > Yes. Back then the bytes shared between BIOS and ACPI were located in a MMIO > memory area of the TPM TIS, which was basically a hack to save the few bytes > across reboot. This time we are trying to embed these bytes in the ACPI > stream where it would be allocated similar to the log area for the TPM. > Besides that there would be a QEMU ACPI table (with name 'QEMU') to get the > address from for that memory area. An ACPI variable would also get that > address and use it in the address field of OperationRegion().
I'm a bit confused by the above. QEMU dynamically generates the ACPI tables today. So, why go through the hoops above - why not just directly generate the ACPI table with whatever info you need? If you need to have some storage across boots, why not create a virtual device and have the ACPI code read/write to that virtual address? As I understand it, this is already done for other devices in QEMU. -Kevin _______________________________________________ SeaBIOS mailing list SeaBIOS@seabios.org https://mail.coreboot.org/mailman/listinfo/seabios
