memory dump

Abhay Amala amalaabhay at ...9...
Thu Dec 3 16:44:18 CET 2015

Thank you Martin for your detailed explanation. It helps me a lot.

I could put the RAM data into a file using the following snippet and get a
file with size 268.4 MB. But when i tried to make some kind memory analysis
on the file, i get something which is different from what i expect. Is this
snippet the right one to do memory imaging? thanks in advance for answers.

         size_t size = Vm_base::ram()->size();
         void* addr = (void*)Vm_base::ram()->local();
         FILE *fd = fopen("memdump.dd", "w+b");
         if(fd != NULL)
                 fwrite(addr, 1, size, fd);


On Thu, Dec 3, 2015 at 11:35 AM, Martin Stein <martin.stein at ...1...>

> Hey Abhay,
> First of all, sorry for the late feedback, last week, I couldn't find
> the time to answer your mail.
> Am 27.11.2015 um 00:19 schrieb Abhay Amala:
> > I am running tz_vmm on imx53qsb and thinking about taking a snapshot of
> > the normal world memory inside the tz_vmm app and put into a file as a
> > raw data. I appreciate if anyone give me a hint.
> Inside the tz_vmm the guest RAM is already mapped. You can get its local
> base address via Vm_base::ram()->local(). Its size can be read via
> Vm_base::ram()->size().
> However, be aware that the state you read from the guest RAM in tz_vmm
> is most probably not up-to-date as the non-secure world uses separate
> caches that do not synchronize with the caches of the secure world. As
> far as I know, there is no way to cause a non-secure cache flush from
> within the secure world. But I might be wrong as I haven't read the
> manual [1] in depth regarding this topic. Maybe it's a solution to
> implement a simple protocol between VMM and VM, using interrupt
> injection and SMCs to requests the guest OS to flush its caches for you.
> Regarding the file you want to create from the read RAM data: It might
> be a good idea to use the SD card as storage medium as an appropriate
> driver [2] already exists. However, the driver provides a Block session
> while you want to use a File_system session in tz_vmm. Assuming, that
> you have formatted your SD partition with FAT32, you can create a
> File_system session out of a Block session by using use ffat_fs. You may
> have a look at the test scripts [3] to receive an impression on how
> ffat_fs is used.
> If you have further questions, don't hesitate to ask ;)
> Cheers,
> Martin
> [1]
> [2] repos/os/src/drivers/sd_card/spec/imx53
> [3]
> repos/libports/run/
> repos/libports/run/
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