On 14 July 2016 at 01:03, Alistair Francis <alistair.fran...@xilinx.com> wrote: > Signed-off-by: Alistair Francis <alistair.fran...@xilinx.com> > --- > V9: > - Clarify the image loading options > V8: > - Improve documentation > V6: > - Fixup documentation > V4: > - Re-write to be more comprehensive > > docs/generic-loader.txt | 63 > +++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 63 insertions(+) > create mode 100644 docs/generic-loader.txt > > diff --git a/docs/generic-loader.txt b/docs/generic-loader.txt > new file mode 100644 > index 0000000..16c11ee > --- /dev/null > +++ b/docs/generic-loader.txt > @@ -0,0 +1,63 @@ > +Copyright (c) 2016 Xilinx Inc. > + > +This work is licensed under the terms of the GNU GPL, version 2 or later. > See > +the COPYING file in the top-level directory. > + > + > +The 'loader' device allows the user to load multiple images or values into > +QEMU at startup. > + > +Loading Memory Values > +--------------------- > +The loader device allows memory values to be set from the command line. This > +can be done by following the syntax below: > + > + -device loader,addr=<addr>,data=<data>,data-len=<len> > + -device loader,addr=<addr>,cpu-num=<cpu-num> > + > + <addr> - The address to store the data or the value to use as the > + CPU's PC. > + <data> - The value to be written to the address. The maximum size of > + the data is 8 bytes. > + <data-len> - The length of the data in bytes. This argument must be > + included if the data argument is. > + <data-be> - Set to true if the data to be stored on the guest should be > + written as big endian data. The default is to write little > + endian data. > + <cpu-num> - This will cause the CPU to be reset and the PC to be set to > + the value of addr. > + > +For all values both hex and decimal values are allowed. By default the values > +will be parsed as decimal. To use hex values the user should prefix the > number > +with a '0x'. > + > +An example of loading value 0x8000000e to address 0xfd1a0104 is: > + -device loader,addr=0xfd1a0104,data=0x8000000e,data-len=4 > + > +Loading Files > +------------- > +The loader device also allows files to be loaded into memory. This can be > done > +similarly to setting memory values. The syntax is shown below: > + > + -device loader,file=<file>,addr=<addr>,cpu-num=<cpu-num>,force-raw=<raw> > + > + <file> - A file to be loaded into memory > + <addr> - The addr in memory that the file should be loaded. This is > + ignored if you are using an ELF (unless force-raw is true). > + This is required if you aren't loading an ELF. > + <cpu-num> - This specifies the CPU that should be used. This is an > + optional argument and will cause the CPU's PC to be set to > + where the image is stored or in the case of an ELF file to > + the value in the header. This option should only be used > + for the boot image. > + This will also cause the image to be written to the > specified > + CPUs address space. > + <force-raw> - Forces the file to be treated as a raw image. This can be > + used to specify the load address of ELF files. > + > +For all values both hex and decimal values are allowed. By default the values > +will be parsed as decimal. To use hex values the user should prefix the > number > +with a '0x'. > + > +An example of loading an ELF file which CPU0 will boot is shown below: > + -device loader,file=./images/boot.elf,cpu-num=0
With this interface, you can specify a file to be loaded to CPU 2's address space (via file=whatever,cpu-num=2) but you can't specify a data value to be loaded to CPU 2's address space (because addr=a,data=x,data-len=y,cpu-num=2 isn't valid). I think we could usefully make that syntax do that. This is probably most clearly documented by completely splitting -device loader,addr=<addr>,cpu-num=<cpu-num> (set the PC) from -device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>] (load raw data values) in the documentation in the same way that loader,file is split. (I have a feeling we've been circling around on this option syntax over the last few revisions so apologies if I've been inconsistent.) You also can't specify a file to be loaded which doesn't set the CPU PC, but I'm not sure how important that is. We can always add it later with a no-set-pc option flag if we need it I guess. thanks -- PMM
