Re: [EXTERNAL][PATCH] mips/mips_malta: Allow more than 2G RAM

[Aleksandar Markovic]

Forwarding this to Igor. Can you please give us your opinion, Igor, on this 
proposal?

________________________________________
From: Jiaxun Yang <jiaxun.y...@flygoat.com>
Sent: Friday, February 28, 2020 4:26 AM
To: qemu-devel@nongnu.org
Cc: phi...@redhat.com; Aleksandar Markovic; Jiaxun Yang; Yunqiang Su
Subject: [EXTERNAL][PATCH] mips/mips_malta: Allow more than 2G RAM

When malta is coupled with MIPS64 cpu which have 64bit
address space, it is possible to have more than 2G RAM.

So we removed ram_size check and overwrite memory
layout for these targets.

Signed-off-by: Jiaxun Yang <jiaxun.y...@flygoat.com>
Suggested-by: Yunqiang Su <y...@wavecomp.com>
---
 hw/mips/mips_malta.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/hw/mips/mips_malta.c b/hw/mips/mips_malta.c
index 6e7ba9235d..de89cdcfc1 100644
--- a/hw/mips/mips_malta.c
+++ b/hw/mips/mips_malta.c
@@ -98,7 +98,8 @@ typedef struct {
 } MaltaState;

 static struct _loaderparams {
-    int ram_size, ram_low_size;
+    unsigned int ram_low_size;
+    ram_addr_t ram_size;
     const char *kernel_filename;
     const char *kernel_cmdline;
     const char *initrd_filename;
@@ -1023,6 +1024,7 @@ static int64_t load_kernel(void)
 {
     int64_t kernel_entry, kernel_high, initrd_size;
     long kernel_size;
+    char mem_cmdline[128];
     ram_addr_t initrd_offset;
     int big_endian;
     uint32_t *prom_buf;
@@ -1099,20 +1101,28 @@ static int64_t load_kernel(void)
     prom_buf = g_malloc(prom_size);

     prom_set(prom_buf, prom_index++, "%s", loaderparams.kernel_filename);
+
+    /*
+     * Always use cmdline to overwrite mem layout
+     * as kernel may reject large emesize.
+     */
+    sprintf(&mem_cmdline[0],
+        "mem=0x10000000@0x00000000 mem=0x%" PRIx64 "@0x90000000",
+        loaderparams.ram_size - 0x10000000);
     if (initrd_size > 0) {
         prom_set(prom_buf, prom_index++,
-                 "rd_start=0x%" PRIx64 " rd_size=%" PRId64 " %s",
-                 xlate_to_kseg0(NULL, initrd_offset),
+                 "%s rd_start=0x%" PRIx64 " rd_size=%" PRId64 " %s",
+                 &mem_cmdline[0], xlate_to_kseg0(NULL, initrd_offset),
                  initrd_size, loaderparams.kernel_cmdline);
     } else {
-        prom_set(prom_buf, prom_index++, "%s", loaderparams.kernel_cmdline);
+        prom_set(prom_buf, prom_index++, "%s %s",&mem_cmdline[0] 
,loaderparams.kernel_cmdline);
     }

     prom_set(prom_buf, prom_index++, "memsize");
     prom_set(prom_buf, prom_index++, "%u", loaderparams.ram_low_size);

     prom_set(prom_buf, prom_index++, "ememsize");
-    prom_set(prom_buf, prom_index++, "%u", loaderparams.ram_size);
+    prom_set(prom_buf, prom_index++, "%lu", loaderparams.ram_size);

     prom_set(prom_buf, prom_index++, "modetty0");
     prom_set(prom_buf, prom_index++, "38400n8r");
@@ -1253,12 +1263,14 @@ void mips_malta_init(MachineState *machine)
     /* create CPU */
     mips_create_cpu(machine, s, &cbus_irq, &i8259_irq);

-    /* allocate RAM */
+#ifdef TARGET_MIPS32
+    /* MIPS32 won't accept more than 2GiB RAM due to limited address space */
     if (ram_size > 2 * GiB) {
         error_report("Too much memory for this machine: %" PRId64 "MB,"
                      " maximum 2048MB", ram_size / MiB);
         exit(1);
     }
+#endif

     /* register RAM at high address where it is undisturbed by IO */
     memory_region_add_subregion(system_memory, 0x80000000, machine->ram);
--
2.25.1