Paolo Bonzini <pbonzini@...>
On 22/08/19 20:29, Laszlo Ersek wrote:
On 08/22/19 08:18, Paolo Bonzini wrote:It's much simpler: these ranges are not in e820, for exampleOn 21/08/19 22:17, Kinney, Michael D wrote:This thread (esp. Jiewen's and Mike's messages) are the first time thatDMA protection of memory ranges is a chipset feature. For the currentYes.
kernel: BIOS-e820: [mem 0x0000000000059000-0x000000000008bfff] usable
kernel: BIOS-e820: [mem 0x000000000008c000-0x00000000000fffff] reserved
The ranges are not special-cased in any way by QEMU. Simply, AB-segs
and TSEG RAM are not part of the address space except when in SMM.
Therefore, DMA to those ranges ends up respectively to low VGA RAM
and to the bit bucket. When AB-segs are open, for example, DMA to that
area becomes possible.
 old timers may remember DEF SEG=&HB800: BLOAD "foo.img",0. It still
works with some disk device models.