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Fri, 06 Mar 2026 05:29:55 -0800 (PST) From: Soumyajyotii Ssarkar To: xen-devel@lists.xenproject.org, sarkarsoumyajyoti23@gmail.com Cc: Jan Beulich , "Daniel P . Smith" , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= , Andrew Cooper , Soumyajyotii Ssarkar Subject: [PATCH v2 3/3] x86/efi: Add opt-out mechanism for BGRT preservation Date: Fri, 6 Mar 2026 18:59:35 +0530 Message-ID: <20260306132935.13727-4-soumyajyotisarkar23@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260306132935.13727-1-soumyajyotisarkar23@gmail.com> References: <20260306132935.13727-1-soumyajyotisarkar23@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1772803821171158500 Content-Type: text/plain; charset="utf-8" As described in the task, BGRT preservation is now enabled by default to fi= x ACPI corruption for desktop/workstation systems (similar to ESRT). Add an opt-out parameter 'efi=3Dno-bgrt' to allow disabling BGRT preservation on systems where the ~1MB memory overhead is not desired. The parameter is parsed during normal Xen boot (not during EFI phase), so it only affects diagnostic logging. The opt-out flag is checked at the start of efi_preserve_bgrt_img(). Usage: Default: BGRT preserved automatically Opt-out: Add 'efi=3Dno-bgrt' to Xen command line Signed-off-by: Soumyajyotii Ssarkar --- xen/common/efi/boot.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c index 1e3489e902..b735eac6b2 100644 --- a/xen/common/efi/boot.c +++ b/xen/common/efi/boot.c @@ -167,6 +167,7 @@ static SIMPLE_TEXT_OUTPUT_INTERFACE *__initdata StdErr; static UINT32 __initdata mdesc_ver; static bool __initdata map_bs; +static bool __initdata opt_bgrt_disabled =3D false; static struct file __initdata cfg; static struct file __initdata kernel; @@ -868,6 +869,9 @@ static void __init efi_preserve_bgrt_img(EFI_SYSTEM_TAB= LE *SystemTable) bgrt_debug_info.preserved =3D false; bgrt_debug_info.failure_reason =3D NULL; + if ( opt_bgrt_disabled ) + return; + bgrt =3D find_bgrt_table(SystemTable); if ( !bgrt ) { @@ -1873,6 +1877,10 @@ static int __init cf_check parse_efi_param(const cha= r *s) else __clear_bit(EFI_RS, &efi_flags); } + else if ( (ss - s) =3D=3D 7 && !memcmp(s, "no-bgrt", 7) ) + { + opt_bgrt_disabled =3D true; + } else if ( (ss - s) > 5 && !memcmp(s, "attr=3D", 5) ) { if ( !cmdline_strcmp(s + 5, "uc") ) @@ -1968,7 +1976,11 @@ void __init efi_init_memory(void) if ( !efi_enabled(EFI_BOOT) ) return; - if ( bgrt_debug_info.preserved ) + if ( opt_bgrt_disabled ) + { + printk(XENLOG_INFO "EFI: BGRT preservation disabled\n"); + } + else if ( bgrt_debug_info.preserved ) { printk(XENLOG_INFO "EFI: BGRT image preserved: %u KB\n", bgrt_debug_info.size / 1024); -- 2.53.0