On 10/2/23 13:11, marcandre.lur...@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lur...@redhat.com>
>
> Implementing RAMFB migration is quite straightforward. One caveat is to
> treat the whole RAMFBCfg as a blob, since that's what is exposed to the
> guest directly. This avoid having to fiddle with endianness issues if we
> were to migrate fields individually as integers.
>
> The following patches turns the migration only on machine >= 8.2.
>
> Fixes:
> https://bugzilla.redhat.com/show_bug.cgi?id=1859424
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> ---
> hw/display/ramfb.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/hw/display/ramfb.c b/hw/display/ramfb.c
> index 79b9754a58..4aaaa7d653 100644
> --- a/hw/display/ramfb.c
> +++ b/hw/display/ramfb.c
> @@ -12,6 +12,7 @@
> */
>
> #include "qemu/osdep.h"
> +#include "migration/vmstate.h"
> #include "qapi/error.h"
> #include "hw/loader.h"
> #include "hw/display/ramfb.h"
> @@ -28,6 +29,8 @@ struct QEMU_PACKED RAMFBCfg {
> uint32_t stride;
> };
>
> +typedef struct RAMFBCfg RAMFBCfg;
> +
> struct RAMFBState {
> DisplaySurface *ds;
> uint32_t width, height;
> @@ -115,6 +118,23 @@ void ramfb_display_update(QemuConsole *con, RAMFBState
> *s)
> dpy_gfx_update_full(con);
> }
>
> +static int ramfb_post_load(void *opaque, int version_id)
> +{
> + ramfb_fw_cfg_write(opaque, 0, 0);
> + return 0;
> +}
> +
> +static const VMStateDescription vmstate_ramfb = {
> + .name = "ramfb",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .post_load = ramfb_post_load,
> + .fields = (VMStateField[]) {
> + VMSTATE_BUFFER_UNSAFE(cfg, RAMFBState, 0, sizeof(RAMFBCfg)),
I just couldn't figure out, from code review, why VMSTATE_BUFFER would
not work here. So I applied your patches, changed this like follows:
diff --git a/hw/display/ramfb.c b/hw/display/ramfb.c
index 077fd2fa2c31..04bf01059994 100644
--- a/hw/display/ramfb.c
+++ b/hw/display/ramfb.c
@@ -131,7 +131,7 @@ static const VMStateDescription vmstate_ramfb = {
.minimum_version_id = 1,
.post_load = ramfb_post_load,
.fields = (VMStateField[]) {
- VMSTATE_BUFFER_UNSAFE(cfg, RAMFBState, 0, sizeof(RAMFBCfg)),
+ VMSTATE_BUFFER(cfg, RAMFBState),
VMSTATE_END_OF_LIST()
}
};
and tried to build it.
I got a wall of error messages about cryptic macro nesting.
I'm quite annoyed that nearly none of the VMSTATE_ macros are
documented; even git-blame tends to be unhelpful. Ultimately though,
there was one useful bit in the wall of error messages: the error was
related to "type_check_array".
Upon reviewing type_check_array, my impression is that VMSTATE_BUFFER is
suitable only for *array fields*. I randomly picked an existent example,
namely
static const VMStateDescription bulk_in_vmstate = {
.name = "CCID BulkIn state",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_BUFFER(data, BulkIn),
VMSTATE_UINT32(len, BulkIn),
VMSTATE_UINT32(pos, BulkIn),
VMSTATE_END_OF_LIST()
}
};
from "hw/usb/dev-smartcard-reader.c", and sure enough, "data" is an
array field in BulkIn:
typedef struct BulkIn {
uint8_t data[BULK_IN_BUF_SIZE];
uint32_t len;
uint32_t pos;
} BulkIn;
So that's the reason.
Again, annoying lack of documentation, but I agree that your
VMSTATE_BUFFER_UNSAFE application is judicious.
Thanks!
Laszlo
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> RAMFBState *ramfb_setup(Error **errp)
> {
> FWCfgState *fw_cfg = fw_cfg_find();
> @@ -127,6 +147,7 @@ RAMFBState *ramfb_setup(Error **errp)
>
> s = g_new0(RAMFBState, 1);
>
> + vmstate_register(NULL, 0, &vmstate_ramfb, s);
> rom_add_vga("vgabios-ramfb.bin");
> fw_cfg_add_file_callback(fw_cfg, "etc/ramfb",
> NULL, ramfb_fw_cfg_write, s,
