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x86: emulation: Set an MTRR for the RAM

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QEMU likes to have an MTRR set up, just like real machines. Add an MTRR
which covers the total RAM size.

This does nothing on machines without MTRRs.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass 2025-03-15 14:25:47 +00:00 • committed by Tom Rini
parent 66c9ade35b
commit 790baef3b9
1 changed files with 18 additions and 0 deletions
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18
arch/x86/cpu/qemu/dram.c
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@ -4,7 +4,9 @@
*/
#include <init.h>
#include <spl.h>
#include <asm/global_data.h>
#include <asm/mtrr.h>
#include <asm/post.h>
#include <asm/arch/qemu.h>
#include <linux/sizes.h>
@ -44,6 +46,22 @@ int dram_init(void)
gd->ram_size += qemu_get_high_memory_size();
post_code(POST_DRAM);
if (xpl_phase() == PHASE_BOARD_F) {
u64 total = gd->ram_size;
int ret;
if (total > SZ_2G + SZ_1G)
total += SZ_1G;
ret = mtrr_add_request(MTRR_TYPE_WRBACK, 0, total);
if (ret != -ENOSYS) {
if (ret)
return log_msg_ret("mta", ret);
ret = mtrr_commit(false);
if (ret)
return log_msg_ret("mtc", ret);
}
}
return 0;
}