qemu-patch-raspberry4/hw/pci-host
Eduardo Habkost e33d22fab3 piix: Document coreboot-specific RAM size config register
The existing i440fx initialization code sets a PCI config register that
isn't documented anywhere in the Intel 440FX datasheet. Register 0x57 is
DRAMC (DRAM Control) and has nothing to do with the RAM size.

This was implemented in commit ec5f92ce6a
because old coreboot code tried to read registers 0x5a-0x5f,0x56,0x57 to
get the RAM size from QEMU, but I couldn't find out why coreboot did
that. I assume it was a mistake, and the original code was supposed to
be reading the DRB[0-7] registers (offsets 0x60-0x67).

Document that coreboot-specific register offset in a macro and a
comment, for future reference.

Cc: Ed Swierk <eswierk@skyportsystems.com>
Cc: Richard Smith <smithbone@gmail.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2015-08-13 14:08:25 +03:00
..
apb.c Switch non-CPU callers from ld/st*_phys to address_space_ld/st* 2015-04-26 16:49:24 +01:00
bonito.c Convert (ffs(val) - 1) to ctz32(val) 2015-04-28 15:36:08 +02:00
gpex.c pci: Add generic PCIe host bridge 2015-02-13 05:46:07 +00:00
grackle.c pci: Trivial device model conversions to realize 2015-02-26 12:42:16 +01:00
Makefile.objs pci: Add generic PCIe host bridge 2015-02-13 05:46:07 +00:00
pam.c hw/i386: remove smram_update 2015-06-05 17:36:39 +02:00
piix.c piix: Document coreboot-specific RAM size config register 2015-08-13 14:08:25 +03:00
ppce500.c pci: Trivial device model conversions to realize 2015-02-26 12:42:16 +01:00
prep.c exec.c: Make address_space_rw take transaction attributes 2015-04-26 16:49:24 +01:00
q35.c q35: implement TSEG 2015-06-05 19:45:13 +02:00
uninorth.c uninorth: convert ffs(3) to ctz32() 2015-04-28 15:36:08 +02:00
versatile.c pci: Trivial device model conversions to realize 2015-02-26 12:42:16 +01:00